Euxenite

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Euxenite
Euxenite - Vegusdal, Norvegia 01.jpg
Euxenite from Norway, around 11 cm of size
General
CategoryOxide minerals
Formula
(repeating unit)
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)
2
O
6
Strunz classification4.DG.05
Crystal systemOrthorhombic
Space groupPcmn (no. 62)
Identification
ColorBlack, brownish black,greenish black
Crystal habitMassive, anhedral crystals in matrix
TwinningCommon on [201]
CleavageNone
FractureConchoidal to subconchoidal
Mohs scale hardness5.5 to 6.5
LusterBrilliant submetallic, waxy to resinous on fractures
StreakYellowish, grayish, or reddish brown
DiaphaneityOpaque, translucent on thin edges
Specific gravity4.7 to 5
Optical propertiesIsotropic
Refractive indexn = 2.06 - 2.24
Other characteristicsMetamict - originally crystalline, now amorphous due to radiation damage. Radioactive.svg 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
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)
2
O
6
.

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 US.[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]