Euxenite

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Euxenite
Euxenite - Vegusdal, Norvegia 01.jpg
Euxenite from Norway, around 11 cm of size
General
Category Oxide minerals
Formula (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)
2O
6
IMA symbol Eux [1]
Strunz classification 4.DG.05
Crystal system Orthorhombic
Space group Pcmn (no. 62)
Identification
ColorBlack, brownish black, greenish black
Crystal habit Massive, anhedral crystals in matrix
Twinning Common on [201]
Cleavage None
Fracture Conchoidal to subconchoidal
Mohs scale hardness5.5 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 propertiesIsotropic
Refractive index n = 2.06 – 2.24
Other characteristics Metamict – originally crystalline, now amorphous due to radiation damage. Radioactive.svg Radioactive
References [2] [3] [4]

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

Contents

Chemistry

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)
2 O
6. It is commonly partially amorphous due to radiation damage.

Euxenite forms a continuous series with the titanium rich polycrase-(Y) having the formula (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)
2O
6.

Name and discovery

It was first described in 1870 and named for from the Greek (εὔξενος), hospitable or friendly to strangers, in allusion to the many rare elements that it contains. [4] [3]

Occurrence

It occurs in granite pegmatites and detrital black sands. [2]

It is found in many locations worldwide, notably its type locality in Jølster, Sunnfjord, Norway. [3] Other locations include the Ural Mountains of Russia; Sweden; Minas Gerais, Brazil; Ampangabe, Madagascar; Ontario, Canada; and in Arizona, Wyoming and Colorado in the US. [5]

Use

Euxenite is used as an ore of the rare earth elements it contains. Rare large crystals have also been used in jewelry. [5]

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 http://rruff.geo.arizona.edu/doclib/hom/euxenitey.pdf Minderal Handbook
  3. 1 2 3 http://webmineral.com/data/Euxenite-(Y).shtml Webmineral data
  4. 1 2 http://www.mindat.org/min-1425.html Mindat
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