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Euxenite
Chemical Formula	(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Species	Oxides & Hydroxides
Crystal System	Orthorhombic
Mohs Scale	5.5-6.5
Specific Gravity	4.7-5
Color	Black, brownish black,greenish black
Streak	Yellowish, grayish, or reddish brown
Luster	Brilliant submetallic, waxy to resinous on fractures
Refractive Index	n = 2.06 - 2.24
Diaphaneity	Opaque, translucent on thin edges
Cleavage	None
Fracture	Conchoidal to subconchoidal
Crystal Habit：Massive, anhedral crystals in matrix

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)₂O₆. It is commonly partially amorphous due to radiation damage.

Name and discovery

It was first described in 1870 and named for from the Greek (ε?ξεινο?), hospitable or friendly to strangers, in allusion to the many rare elements that it contains.

Occurrence

It occurs in granite pegmatites and detrital black sands.

It is found in many locations worldwide, notably its type locality in J?lster, Sunnfjord, Norway. 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.

Use

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