Euxenite

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Euxenite
Euxenite from Norway, around 11 cm of size
General
Category	Oxide mineral
Chemical formula	(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Identification
Color	Black, brownish black,greenish black
Crystal habit	Massive, anhedral crystals in matrix
Crystal system	Orthorhombic
Twinning	Common on [201]
Cleavage	None
Fracture	Conchoidal to subconchoidal
Mohs Scale hardness	5.5 to 6.5
Luster	Brilliant submetallic, waxy to resinous on fractures
Refractive index	n = 2.06 - 2.24
Optical Properties	Isotropic
Streak	Yellowish, grayish, or reddish brown
Specific gravity	4.7 to 5
Diaphaneity	Opaque, translucent on thin edges
Other Characteristics	Metamict - originally crystalline, now amorphous due to radiation damage. Radioactive
References	[1][2][3]

Euxenite or euxenite-Y is a brownish black mineral with a metallic luster. It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)₂O₆. It occurs in granite pegmatites and detrital black sands.^[1] It is commonly partially amorphous due to radiation damage.

It was first described in 1870 and named for From the Greek (εΰζευος), hospitable or friendly to strangers, in allusion to the many rare elements that it contains.^[3][2]

It is found in many locations worldwide, notably its type locality in Jolster, Sondfjord, Norway.^[2] Other locations include include the Ural Mountains of Russia; Sweden; Minas Gerais, Brazil; Ampangabe, Madagascar; Ontario, Canada; and in Arizona, Wyoming and Colorado in the U. S. A.^[4]

Euxenite is used as an ore of the rare earth elements it contains. Rare large crystals have also been used in jewelry.^[4]

[edit] References

1. ^ ^{a b} http://rruff.geo.arizona.edu/doclib/hom/euxenitey.pdf Minderal Handbook
2. ^ ^{a b c} http://webmineral.com/data/Euxenite-(Y).shtml Webmineral data
3. ^ ^{a b} http://www.mindat.org/min-1425.html Mindat
4. ^ ^{a b} http://www.galleries.com/minerals/oxides/euxenite/euxenite.htm Mineral Galleries