Monazite may be partially metamict, with N=1.79. Stones can be an attractive yellow or brown color but are usually small.
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|Crystallography||Monoclinic. Crystals small, tabular, wedge-shaped; faces often rough or uneven; also massive, granular; detrital.|
|Colors||Brown, reddish brown, yellowish brown, pink, yellow, greenish, grayish white, white.|
|Luster||Vitreous to subadamantine; resinous; waxy.|
|Cleavage||Distinct 1 direction, sometimes perfect. Fracture conchoidal to uneven. Brittle.|
|Stone Sizes||Faceted gems would normally be under 5 carats, either from Swiss crystals or from portions of crystals from other localities. Facetable material is very rare and cut stones are absent from all but a few private collections. Large cabochons could be cut from various large crystals that have been found.|
|Spectral||Extremely complex spectra observed, mostly rare earth types.|
|Pleochroism||Faint or none (yellowish shades). Sri Lanka=material=reddish orange/golden yellow.|
Optics: a=1.774-1.800; β= 1.777-1.801; γ= 1.828-1849.
Biaxial (+), 2V= 11-15°.
Higher refractive index is accompanied by lower birefringence.
Occurrence: An accessory mineral in igneous rocks and gneisses; sometimes in large crystals in granite pegmatites; as a detrital mineral in sands.
Petaca district, New Mexico; Amelia, Virginia.
Colorado: fine crystals.
Wyoming: crystals to several pounds.
Madagascar: in fine crystals.
Switzerland: excellent crystals in alpine vein deposits.
Sri Lanka: orange pebbles.
Callipampa, Bolivia: good crystals.
Deposits of alluvial material in Australia, India, Brazil, Malaya, Nigeria.
Comments: Monazite may be partially metamict, with N=1.79. Stones can be an attractive yellow or brown color but are usually small.
Name: From the Greek monazein, to be solitary, because of the rarity of the mineral.