Purple Passion
This purple agate ( purple passion) from Ojo Laguna, Chihuahua, Mexico, is sometimes referred to as amethystine agate. Varieties such as Purple Passion and other Laguna agates originate from the Sierra Tarahumara region of the Sierra Madre Occidental Mountains where the nodules occur in andesitic volcanic rocks.
Agate is a variety of cryptocrystalline quartz that typically contains 1–20% of the mineral moganite. Both quartz and moganite are forms of silicon dioxide (SiO₂) but differ in crystal structure—a phenomenon known as polymorphism. Because the crystals are too small to be seen without powerful magnification, agate is described as cryptocrystalline, meaning “hidden crystals.”
In this specimen, discrete purple crystals are visible in some bands—these are macrocrystals of a quartz variety known as amethyst. Amethyst, both macrocrystalline and cryptocrystalline, owes its violet color to irradiation from nearby radioactive minerals, along with impurities of iron (Fe³⁺) and, in some cases, other transition metals.
This specimen was photographed at the 2025 Wyoming State Gem and Mineral Show in Gillette, Wyoming.
Purple Passion
This purple agate ( purple passion) from Ojo Laguna, Chihuahua, Mexico, is sometimes referred to as amethystine agate. Varieties such as Purple Passion and other Laguna agates originate from the Sierra Tarahumara region of the Sierra Madre Occidental Mountains where the nodules occur in andesitic volcanic rocks.
Agate is a variety of cryptocrystalline quartz that typically contains 1–20% of the mineral moganite. Both quartz and moganite are forms of silicon dioxide (SiO₂) but differ in crystal structure—a phenomenon known as polymorphism. Because the crystals are too small to be seen without powerful magnification, agate is described as cryptocrystalline, meaning “hidden crystals.”
In this specimen, discrete purple crystals are visible in some bands—these are macrocrystals of a quartz variety known as amethyst. Amethyst, both macrocrystalline and cryptocrystalline, owes its violet color to irradiation from nearby radioactive minerals, along with impurities of iron (Fe³⁺) and, in some cases, other transition metals.
This specimen was photographed at the 2025 Wyoming State Gem and Mineral Show in Gillette, Wyoming.