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www.mineralgallery.co.za Minerals F-J |
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Herderite |
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Name
Herderite
Chemistry
CaBe(PO4)F
Uses
Sometimes used as a precious stone (facets, cabochons) Otherwise used as a mineral specimen.
Color
Colourless, pale yellow, greenish-white
Hardness
5-5.5
Specific gravity
2.9 to 3
Crystal system:
Monoclinic. Crystals stout prismatic or thick tabular. Commonly pseudo orthorombic. include prismatic crystals with a complex, but over all domal termination. The prism faces may be rounded and etched. Twinning is common forming cyclic twins that have a malformed hexagonal tabular crystal.
Accompanied by:
Microcline and minerals common to phosphatic grantite pegamtites
Fracture
Subconchoidal
Luster
vitreous
Cleavage
Poor cleavage indistinct in two directions.
Streak
white
Similar to:
Aquamarine
Type Locality: Ehrenfriedersdorf, Sachsen (Saxony), Germany. Phosphate strucurally related to Gadolinite Group. Brazil
It forms good crystals and can have a nice yellow or light blue color.
Locations where the mineral has been found.
Brazil
Northeast Region Paraíba Campina Grande
Southeast Region Minas Gerais
Rio Doce Governador Valadares Divino das Laranjeiras Linópolis Alto do Corrego Frio
Galiléia Lavra do Énio pegmatite [MinRec 12:69] Golconda District
Namibia
Erongo, Namibia
See the following URL for more localities. http://www.mindat.org/min-1876.html
It is known under many names.
Synonyms: Allogonit, Allogonita, Allogonite, Fluor-herderite, Glucinit, Glucinita, Glucinite, Herderit, Herderita
Type Locality: Sauberg Mine, Ehrenfriedersdorf, Erzgebirge, Saxony, Germany . The year of discovery was 1828
Herderite is an attractive and except in some mines in New England, a rather scarce phosphate mineral.
It is not soluble in acids
Good crystals are scarce.
To top-off this mineral, some specimens are fluorescent. A deep blue color can sometimes be seen under longwave ultraviolet light. Herderite, with its beryllium chemistry, possible fluorescence and both attractive and interesting crystal forms, is certainly a nice addition to anybody's collection
It belongs to the phosphates group.
Thermoluminescent, meaning it may glow with a weak blue light upon extreme heating (but this test may damage the specimen). Also sometimes fluorescent, showing deep blue in longwave ultraviolet light
Its twinned crystals are its most note-worthy form although its simple prismatic crystals can have quite complex and interesting terminations. The twinning can produce some very non-monoclinic looking crystals that could easily confuse identification. Orthorhombic and nearly hexagonal twins are possible. A "fishtail" twin has also been seen from deposits in Brazil.
