Euxenite

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Euxenite
Euxenite - Vegusdal, Norvegia 01.jpg
Euxenite from Norway, around 11 cm of size
General
Category Oxide minerals
Formula
(repeating unit)
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Strunz classification 04.DG.05
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
Streak Yellowish, grayish, or reddish brown
Diaphaneity Opaque, translucent on thin edges
Specific gravity 4.7 to 5
Optical properties Isotropic
Refractive index n = 2.06 - 2.24
Other characteristics Metamict - originally crystalline, now amorphous due to radiation damage. Radioactive
References [1][2][3]

Euxenite or euxenite-(Y) (a correct mineralogical name) is a brownish black mineral with a metallic luster.

Chemistry[edit]

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 is commonly partially amorphous due to radiation damage.

Euxenite forms a continuous series with the titanium rich polycrase-(Y) having the following formula: (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6

Name and discovery[edit]

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

Occurrence[edit]

It occurs in granite pegmatites and detrital black sands.[1]

It is found in many locations worldwide, notably its type locality in Jølster, Sunnfjord, Norway.[2] Other locations 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]

Use[edit]

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

References[edit]

  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