Synthetic Selenite (from garden marble rocks)

Synthetic Selenite (from garden marble rocks)

 

Hydrated calcium sulfate (selenite) was made by combining hot solutions of calcium chloride (from garden marble rocks dissolved in muriatic acid) and sodium sulfate. The resulting precipitate was then washed, dried and redissovlved in cold water. After a few weeks, the solution crystallized into clear acicular radiating crystals.

 

Interestingly, there appears to be a contaminent (possibly manganese) from the garden marble rocks. This is seen by a bright orange fluorescence under UVc. Could this be NaCl:Mn that remained after washing? Orange fluorescing halite normally requires a sensitizer to allow UV energy to be efficiently absorbed by the NaCl:Mn however, no lead or copper was added. Mysterious...

 

This experiment was suggested by Flickr's "fluospook" (Axel Emmermann).

 

 

Top - White light view, UVa view

Bottom - UVc view, PHOS view

 

 

Key:

WL = White light

FL = Fluoresces

PHOS = Phosporesces

UVa = 368nm (LW), UVb = 311nm (MW), UVc = 254nm (SW)

'>' = "stimulated by:"

 

18 Watt Triple Output UV lamp from Polman Minerals - Way Too Cool UV lamps

Done