View allAll Photos Tagged cherts
Flint from the Pennsylvanian of Ohio, USA. (cut surface; ~11.9 centimeters across at its widest)
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin. Some Pennsylvanian-aged cherts in eastern America are inferred to be ultimately derived from quartzose eolian dust on seafloors.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park. Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
Mostly subtle pinstripe banding is present in this specimen at left. Near the bottom is a wedge-shaped feature defined by two thin fractures with preferentially stained flint between. The dark yellowish and reddish coloration in the sample is from iron oxide(s). Irregularly-shaped vugs have been filled with slightly bluish-gray chalcedony and megaquartz (= visible quartz crystals in a chert).
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pits in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
This hypertufa pot is about 18 years old. I still love it. Want to make a few more this summer.
Tenuous Link: Pearls to Oyster shells
Magadi Chert, Lake Magadi, Southern Kenya Rift, size 10 cm, shot with a Nikon Z fc with a Nikkor Z MC 50 mm 1:2.8.
Locality: Burro Creek, Arizona
SC2-2664
Note: The dark colored spots are incipient magnesium dendrites.
This is a close up view of:
www.flickr.com/photos/usageology/47172181261/in/photostream/
(~12.6 centimeters across at its widest)
Bloodstone is a chert-like rock that is composed of cryptocrystalline quartz. It consists of a mix of deep green and deep red quartz. By itself, deep green cryptocrystalline quartz is called "plasma", and the deep red variety is called "jasper". Bloodstone, or "heliotrope", is plasma with spots or streaks or patches of jasper.
I have never in my life seen a bloodstone sample with provenance information. Surprisingly, there is little to no technical geologic literature on bloodstone - at least, none that is available and out in the open.
This specimen has zero information about its locality and geologic context. Many claim that most bloodstone comes from India. If this sample is Indian in origin, it is possibly derived from a fracture fill in Deccan Traps basalt lava flows (= Cretaceous-Tertiary boundary times), and possibly from the Kathiawar Peninsula in western India.
Bloodstone is also supposedly known from California and Italy.
Rottenstone in the Pennsylvanian of Ohio, USA.
This ugly specimen is a scarce, distinctive rock type called rottenstone, also called tripoli. It forms by extreme, long-term weathering. This rottenstone is after chert (flint) at Flint Ridge, Ohio. In this area, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Many rottenstone samples at this site have weathering spherulites, which superficially resemble oolites (= sand-sized, subspherical, well-rounded, concentrically layered, calcium carbonate grains that form by back-and-forth rolling from wave action in shallow water). This specimen lacks obvious spherulites.
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pit in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
Crinoidal vuggy chert (chertified crinoidal limestone) from the Carboniferous of Ukraine.
Many fossils of shelly organisms (e.g., bivalves, gastropods, brachiopods, cephalopods) have had the original hard parts dissolved away. In such cases of dissolution, the fossil itself is an impression of the outside of the shell (external mold) or an impression of the inside of the shell (internal mold).
This visually intriguing rock is vuggy fossiliferous chert with a partial crinoid stem mold. Crinoids are marine, sessile, benthic, filter-feeding, stalked echinoderms (basically a starfish on a stick). The stem, or stalk, of a crinoid is the most commonly found part in the fossil record. The stem consisted of stacked columnals composed of calcite (CaCO3 - calcium carbonate). The crinoid stem seen here was originally in fossiliferous limestone that has been chertified. The rock is now composed of cryptocrystalline quartz. The calcitic crinoid stem material has dissolved away, leaving a mold.
Stratigraphy: undetermined.
Age: Carboniferous (possibly Tournaisian to lower Visean - Lower Mississippian to lower Middle Mississippian).
Locality: limestone quarry on the western side OR on just south of the town of Komsomolske (Komsomolskiy/Komsomolsky/Komsomolskoe), southeastern Ukraine
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See info. at:
Detail of an eroded canyon wall of chert in a tributary ravine to the Shiraiwa Ravine in Saitama, Japan.
Flint from the Pennsylvanian of Ohio, USA.
Flint is the state gemstone of Ohio. "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. In early times, light-colored material was called "chert" and dark-colored material was called "flint". Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules). Another proposed origin for some chert / flint is altered quartzose eolian dust deposits on ancient seafloors.
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric Americans quarried the Vanport Flint at many specific sites on Flint Ridge. Old flint pits can be seen along hiking trails in Flint Ridge State Park ("Flint Ridge State Memorial"; "Flint Ridge Ancient Quarries & Nature Preserve"). Many prehistoric artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
The orangish-brown area in this sample is extremely weathered flint - this is called rottenstone or tripoli. The rounded structures that resemble oolites are actually weathering spherulites (click on the photo once or twice to zoom in).
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pit in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
Flint from the Pennsylvanian of Ohio, USA.
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.
Studies done by geologists at Ohio State University at Newark indicate that the Vanport Flint has a relatively complex history, the details of which are still being worked out.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park ("State Memorial"). Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
This spectacular red-and-dark blue flint sample is a flint knapper's preform. They are often sold to other flint knappers, who process them further into various points. The flint has been heated in a kiln, which is a standard procedure. Heating improves the knappability of the flint. Heating also often intensifies colors.
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Roy Miller Flint Quarries - flint pit just northwest of the Flint Ridge Road-Brownsville Road intersection, near Flint Ridge State Park, central Flint Ridge, southeastern Licking County, east-central Ohio, USA (vicinity of 39° 59’ 21.84" North latitude, 82° 15’ 49.04" West longitude)
Flint-knapped arrowhead.
Knapper: Ed Moreland
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park ("State Memorial"). Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
The arrowhead seen here is a modern replica, produced by a skilled knapper named Ed Moreland. The flint itself comes from a Roy Miller flint pit on Flint Ridge. Material from this site is famous for having greenish and/or bluish coloration, which become intensified with heating.
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Roy Miller flint pit, northwestern corner of the Brownsville Road-Flint Ridge Road intersection, next to Flint Ridge State Park, Flint Ridge, southeastern Licking County, east-central Ohio, USA
Collected along Christopher Creek, Arizona
Image includes specimens collected and two polished cabochons.
Flint-knapped arrowhead. (~6.2 centimeters from top to bottom)
Knapper: Chris Miller
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.
Studies done by geologists at Ohio State University at Newark indicate that the Vanport Flint has a relatively complex history, the details of which are still being worked out.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park ("State Memorial"). Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
The arrowhead shown here is a modern replica, produced by a skilled knapper named Chris Miller. The flint itself comes from a Roy Miller flint pit on Flint Ridge. Material from this site is famous for having greenish and bluish coloration, which become intensified with heating.
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Roy Miller flint pit, northwestern corner of the Brownsville Road-Flint Ridge Road intersection, next to Flint Ridge State Park, Flint Ridge, southeastern Licking County, east-central Ohio, USA
Flint from the Pennsylvanian of Ohio, USA. (cut surface; ~10.4 centimeters across at its widest)
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin. Some Pennsylvanian-aged cherts in eastern America are inferred to be ultimately derived from quartzose eolian dust on seafloors.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park. Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
This specimen has some pinstripe banding (see the dark area at right). At left is a slender feature defined by two thin fractures with preferentially stained flint between. The dark yellowish and reddish coloration in the sample is from iron oxide(s).
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pits in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
Jasper-quartz pebble conglomerate in the Precambrian of Ontario, Canada.
Southeastern Canada's ~2.3 billion year old Lorrain Formation includes some beautiful rocks that rockhounds have nicknamed "puddingstone". This refers to whitish-gray quartzites having common pebbles of red jasper.
The Lorrain Formation is somewhat heterolithic. Published studies mention that the unit has arkoses, subarkoses, quartzites, and jasper-pebble conglomerates. The latter two lithologies are present at the glacially-eroded outcrop seen here. The quartzites were originally sandstones. They have been well cemented and somewhat metamorphosed into very hard rocks. The jasper-pebble conglomerates, or "puddingstones", include clasts of white quartz and reddish jaspilites. Pebble shapes range from rounded to angular. Ordinarily, a sedimentary rock having rounded pebbles is called "conglomerate", and a rock having angular pebbles is called "breccia". This material has both shape categories, but is referred to as "conglomerate" here.
Jaspilite is a type of BIF (banded iron formation). BIFs only formed on Earth during the Precambrian - most are Paleoproterozoic in age. They are the # 1 source of iron ore for the world's steel industry. Numerous specific types of BIFs are known. Jaspilite consists of alternating laters of red and silvery-gray, iron-rich minerals. The red layers are hematite or jasper (= hematitic chert). The silver-gray layers are usually rich in magnetite and/or specular hematite. Jaspilite BIFs outcrop in many areas around Lake Superior, for example in Michigan's Upper Peninsula, Minnesota, and Ontario.
During the Paleoproterozoic, BIFs were subaerially exposed as paleo-outcrops and eroded, producing BIF sediments, including many red jasper pebbles. These mixed with quartz-rich sediments.
Regional studies indicate that the Lorrain Formation was deposited in ancient shallow ocean, lake, delta, and shoreline environments.
Stratigraphy: Lorrain Formation, upper Cobalt Group, Huronian Supergroup, Paleoproterozoic, ~2.3 Ga
Locality: Ottertail Lake Northeast Roadcut - glacial knob on the eastern side of Rt. 638, northeast of Ottertail Lake & southeast of Rock Lake, north-northeast of the town of Bruce Mines, southern Ontario, southeastern Canada (46° 23' 30.59" North latitude, 83° 43’ 10.94" West longitude)
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Some info. synthesized from:
Hadley (1970) - Paleocurrents and origin of Huronian Lorrain Formation, Ontario and Quebec. American Association of Petroleum Geologists Bulletin 54: 850.
(millimeter scale)
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This is an American Indian artifact. Such objects are relatively common and have been collected for many years. Traditionally, the best collecting sites are plowed farmers' fields.
Arrowheads, spearpoints, scrapers, and knives were made from a variety of specific materials, but chert ("flint") was the most commonly used. Chert/flint is a cryptocrystalline, quartzose sedimentary rock. Other materials include obsidian, a black-colored, glassy-textured, extrusive igneous rock. A scarce arrowhead composition is crystalline quartz.
Several flint horizons in Ohio were exploited by prehistoric people. The three most significant were the Vanport Flint, the Upper Mercer Flint, and the Zaleski Flint.
Locality: farmer's field near the town of Glenford, Perry County, east-central Ohio, USA
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historicengland.org.uk/listing/the-list/list-entry/1248192
ST3215 BROADWAY CP BROADWAY VILLAGE
11/10 Church of St Aldhelm and St Eadburgha 4.2.58
GV I
Anglican parish church. C13 chancel and transepts, nave, porch, and tower C15, reseated and chancel refitted C19. Random rubble chert stone, squared and coursed Ham stone tower, Ham stone dressings, slate roofs, coped verges. West tower with north-east stair turret, aisless 2 bay nave, porch abutting south transept, north transept with organ bay in angle with chancel. Crenellated 3-stage tower, crocketed finials in corners, gargoyles and string course, diagonal buttresses rising to 2-light trefoil-headed louvred bell- openings, trefoil-headed 2-light window with continuous hoodmould, 3-light west window resting on hoodmould of C19 west door, lancets to crenellated stair turret; south front 3-light window to nave, gabled single storey porch with south-west diagonal buttress, boot scraper inset, moulded Perpendicular doorway interior render grooved as ashlar with ribbed barrel vault roof, pointed arch inner doorway and old studded door carved with grafitti, probably C17 work, diagonally buttressed south transept, 2-light south window with scratch dial said to be inset into wall below,, but not visible at time of survey (November 1985), 3-light on east front renewed in C19, C19 priest's door, 2-light window, in diagonally buttressed chancel, 3 lancets forming east window, chimney at east gable end of vestry, north front lancet and doorway, 3-light cinquefoil-headed window on east front of north transept, setback buttresses, 3-light uncusped north and west windows, 3-light window to nave. Interior: rendered except for south transept chapel which is squared and coursed Ham stone. No chancel arch, pointed tower arch, arch to north transept, pointed arch with Perpendicular moulding to south transept. Ribbed and cusped wagon roof with floral bosses and wallplate to chancel, ribbed wagon roof to south transept, similar with brattished wallplate to north transept higher nave roof wagon roof with brattished wallplate and no bosses, Depresssed Tudor arch head openings with incised spandrels between chancel and south transept forming hagioscopes, 3 stone steps remain above of former stair. Scalloped rear-arches to east window of south transept and north window of north transept. Double roll moulded arched doorway to stair turret Carved fronts of choir stalls presented 1927, altar front and panelling c1925, piece of tomb stone set into cill of south chancel window with date 1717 visible. Ham stone table with moulded surround to Sara the wife of John Forde, Vicar, died 1621, inscribed in Latin with good lettering. Other memorials of note: to William Fewtrell, died 1777, wall tablet in grey and white marble with obelisk and urn; to John Fewtrell, died 1819, wall tablet with convex centre, white marble on grey slate; to Freeman Smith, died 1801, wall tablet in similar materials of Greek Revival design. Fine Perpendicular octagonal font with each lace divided into 3 trefoil-headed bays containing a central figure flanked by shields, C20 base, Brass lectern. Stained and coloured oak pulpit carved with the Five founds of Our Lord, restored in 1900 when the plaster coating removed and traces of colour were discovered. Remains of mediaval glass in upper lights of east window in north transept, windows in nave dated l934 and 1933, east window dated 1923 and signed J Wippell and Co (Exeter), south window in south tansept dated 1903 west window 1863. Ten Commandments and the Creed painted on 2 panels of tin and set against tower wall. Bells rehung 1931 (i)1672 (ii) 1748 Thomas Bayley,Bridgwater, (iii) l672, (iv) 1798 George Davis Bridgwater,(v) 1583 A rare dedication to the Saxon saint of St Aldhelm who was Bishop of Sherborne and died at Doulting in 709. The church is also dedicated to St Eadburgha,an abbess and granddaughter of King Alfred. The isolation of the church from the village of Broadway, about half a ails to the south-west is attributed to C17 plague. (Photograph in NMR; Pevsner, Buildings of England South and West Somerset, 1958; Anon, Church Guide,nd).
Listing NGR: ST3296715904
Legacy
The contents of this record have been generated from a legacy data system.
Legacy System number:
264065
Legacy System:
LBS
Sources
Books and journals
Pevsner, N, The Buildings of England: South and West Somerset, (1958)
Bloodstone is a chert-like rock that is composed of cryptocrystalline quartz. It consists of a mix of deep green and deep red quartz. By itself, deep green cryptocrystalline quartz is called "plasma", and the deep red variety is called "jasper". Bloodstone, or "heliotrope", is plasma with spots or streaks or patches of jasper.
I have never in my life seen a bloodstone sample with provenance information. Surprisingly, there is little to no technical geologic literature on bloodstone - at least, none that is available and out in the open.
This specimen has zero information about its locality and geologic context. Many claim that most bloodstone comes from India. If this sample is Indian in origin, it is possibly derived from a fracture fill in Deccan Traps basalt lava flows (= Cretaceous-Tertiary boundary times), and possibly from the Kathiawar Peninsula in western India.
Bloodstone is also supposedly known from California and Italy.
Flint from the Pennsylvanian of Ohio, USA. (cut surface; ~10.4 centimeters across at its widest)
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin. Some Pennsylvanian-aged cherts in eastern America are inferred to be ultimately derived from quartzose eolian dust on seafloors.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old Indian flint pits can be examined along hiking trails in Flint Ridge State Park. Many authentic Indian artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
This specimen has some pinstripe banding (see the dark area at left). At right is a slender feature defined by two thin fractures with preferentially stained flint between. The dark yellowish and reddish coloration in the sample is from iron oxide(s).
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pits in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
Flint-knapped arrowhead (modern replica).
Knapper: Mike Dull
Flint is the "official" state gemstone of Ohio (actually, there's no such thing as "official" anything). "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Ryogamisan is a mountain in Saitama Prefecture, Japan. The rocks comprising the mountain include a lot of formations from old seabeds. Chert and limestone appear in stream beds and jutting out from outcroppings, alongside metamorphic rocks. On the hike up to the summit, about 50 minutes or so from the trailhead, red chert can be found in the streambed along the trail.
(~15.6 centimeters tall) (Knapper: Adam Reynolds)
"Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).
Seen here is a knapped spearpoint - it's a modern replica. The rock is "Burlington Chert", derived from a nodule in the limestone-dominated Burlington Formation. The chert has been heat-treated to make it more knappable. Heating can also change the colors to the light pinkish-orangish present in this specimen.
Stratigraphy: Burlington Formation, Mississippian
Locality: unrecorded/undisclosed site in midwestern America
Flint & flint breccia from the Pennsylvanian of Ohio, USA.
Flint is the state gemstone of Ohio. "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. In early times, light-colored material was called "chert" and dark-colored material was called "flint". Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.
Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules). Another proposed origin for some chert / flint is altered quartzose eolian dust deposits on ancient seafloors.
The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.
Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.
Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric Americans quarried the Vanport Flint at many specific sites on Flint Ridge. Old flint pits can be seen along hiking trails in Flint Ridge State Park ("Flint Ridge State Memorial"; "Flint Ridge Ancient Quarries & Nature Preserve"). Many prehistoric artifacts found in Ohio (arrowheads & spearpoints - "projectile points") are composed of Vanport Flint.
Stratigraphy: Vanport Flint, Allegheny Group, upper Middle Pennsylvanian
Locality: Nethers Flint Quarries - flint pit in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude)
Really small mites, there were a good number on the underside of a large piece of chert on the floor of the woods nearby.
The long front legs are used like feelers and are bounced over the surface ahead of them. They have powerful hind legs that can quickly back them up if the front legs find something they don't like.
The easily erodable Kaibab Limestone often forms pockets and sharp edges on any area exposed to the elements.
NPS Photo by Kristen M. Caldon
Kaibab Formation: Thickness: 200-500 ft.
Deposited 270 million years ago, during the Paleozoic Era - Early Middle Permian Period, the Kaibab Formation is the topmost rock layer at the Grand Canyon.
It is largely made up of light colored limestones and is a cliff forming unit.
The Kaibab Formation contains numerous fossils indicative of a warm and shallow water environment, including crinoids, brachiopods, bryozoans, and sponges.
Chert, which forms irregular blobs and nodules, is common in the Kaibab. Chert is composed of silica and, as it is more resistant to weathering, can often be seen protruding from the rock around it.
It often forms where there is an empty space in the rock, such as in a worm burrow. It also forms where an organism made primarily of silica, such as a sponge, has been buried. Most of the sponges in the Kaibab Formation are preserved in chert.
The Kaibab Limestone is also distinct in that it is readily dissolved, resulting in the formation of karst topography on the canyon’s rims.
Numerous caves and sinkholes are present in the Kaibab, particularly on the North Rim.
While the Kaibab Limestone now caps Grand Canyon’s rims, many more rock layers once sat above the Kaibab.
Perhaps as much as one mile (1.6 km) of Mesozoic rock layers once covered the Kaibab Formation. Remnants of these rock layers exist near Grand Canyon, including Cedar Mountain and Red Butte.
Flint from the Mississippian of Tennessee, USA. (~8.9 centimeters across at its widest)
Flint (= chert) is a cryptocrystalline-textured, quartzose sedimentary rock. It can have a biogenic or chemical origin.
Stratigraphy: attributed to the Ft. Payne Formation, Osagean Stage, upper Lower Mississippian
Locality: undisclosed site in Tennessee, USA
(millimeter scale)
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This is an American Indian artifact. Such objects are relatively common and have been collected for many years. Traditionally, the best collecting sites are plowed farmers' fields.
Arrowheads, spearpoints, scrapers, and knives were made from a variety of specific materials, but chert ("flint") was the most commonly used. Chert/flint is a cryptocrystalline, quartzose sedimentary rock. Other materials include obsidian, a black-colored, glassy-textured, extrusive igneous rock. A scarce arrowhead composition is crystalline quartz.
Several flint horizons in Ohio were exploited by prehistoric people. The three most significant were the Vanport Flint, the Upper Mercer Flint, and the Zaleski Flint.
Locality: farmer's field near the town of Glenford, Perry County, east-central Ohio, USA
Took a picture of this yellow colored rock on my walk in Coyote hills yesterday and discovered their long history ...
Nearly as plentiful as the greenstone, bright reddish-orange chert makes up most of the higher hills and pinnacled
outcrops of the Coyote Hills. Chert started its life as silica accumulating on the floors of deep ocean basins. Literally billions of tiny silica-shelled animals called radiolarians
lived, died, and sank to form a jelly-like ooze. Compressed for millennia, this ooze slowly turned into hard, brittle chert. Traces of iron and manganese give the chert its red, yellow, orange, blackish-blue, and green coloration. In many places, thin beds of manganese oxides remain between the chert
layers as thin, glossy bluish-black coatings.
Source: www.sfbayws.org/sites/default/files/tideline_fall_2016.pdf
Crinoidal vuggy chert (chertified crinoidal limestone) from the Carboniferous of Ukraine.
Many fossils of shelly organisms (e.g., bivalves, gastropods, brachiopods, cephalopods) have had the original hard parts dissolved away. In such cases of dissolution, the fossil itself is an impression of the outside of the shell (external mold) or an impression of the inside of the shell (internal mold).
This visually intriguing rock is vuggy fossiliferous chert with partial crinoid stem molds. Crinoids are marine, sessile, benthic, filter-feeding, stalked echinoderms (basically a starfish on a stick). The stem, or stalk, of a crinoid is the most commonly found part in the fossil record. The stem consisted of stacked columnals composed of calcite (CaCO3 - calcium carbonate). The crinoid stems seen here were originally in fossiliferous limestone that has been chertified. The rock is now composed of cryptocrystalline quartz. The calcitic crinoid stems have dissolved away, leaving molds.
Stratigraphy: undetermined / undisclosed
Age: Carboniferous (possibly Tournaisian to lower Visean - Lower Mississippian to lower Middle Mississippian).
Locality: limestone quarry on the western side OR on just south of the town of Komsomolske (Komsomolskiy/Komsomolsky/Komsomolskoe), southeastern Ukraine
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