Cassiterite Value, Price, and Jewelry Information


CASSITERITE: Bolivia (14.25, 3.5). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Cassiterite has tremendous dispersive fire, much more than diamond, that is visible in properly cut pale-colored gems. This lighter-colored material is, however, very rare except in small fragments. Cassiterite is a fine gemstone – it is rather hard, and there is no cleavage problem. It is unfortunate that cuttable rough is so scarce. Cassiterites under 5 carats are not among the rarest of rare stones, but large clean gems definitely are.

Cassiterite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Cassiterite Information

DataValue
NameCassiterite
VarietiesWood Tin
Crystallography Tetragonal. Crystals prismatic, pyramidal; also botryoidal, reniform with a radial fibrous structure. Twinning common.
Colors Brown, brownish black, black, colorless, gray, yellowish, greenish, red.
Luster Adamantine to vitreous; greasy on fracture surfaces.
Fracture Subconchoidal to uneven. Brittle
Hardness 6-7
Specific Gravity 6.7 – 7.1; pure material 6.99
Birefringence 0.098
Cleavage Imperfect.
Dispersion 0.071 (nearly twice that of diamond)
Stone SizesClean Cassiterite gems over 1 carat are quite rare. Masses occur up to several pounds in weight, but these are opaque and are sometimes cut into cabochons. Pale brown to dark brown gems up to 15 carats have been cut; slightly flawed stones up to 25 carats are known, mostly Bolivian material. Private Collection: 9.6 (brownish, Tasmania): 11.83 (brown, England); 28.16 (brownish). Smithsonian Institution (Washington, D.C): 10 (yellow-brown, Bolivia) Devonian Group (Calgary, Alberta, Canada: 14.85, 9.51 (brownish, Bolivia)
Luminescence None
Spectral Not diagnostic
FormulaSnO2 + Fe, Ta, Nb.
Pleochroism Weak to strong; greenish yellow or yellow-brown/red-brown. Most visible in strongly colored crystals.

OPTICS: o= 2.006; e = 2.097 – 2.101

 

Uniaxial (+); anomalously biaxial, 2V = 0-38°, usually in zoned crystals.

OCCURRENCE: Principal ore of tin; occurs in medium to high temperature veins; metasomatic deposits; granite pegmatites; rhyolites; alluvial deposits.

Alaska; Washington; California; Nevada; South Dakota; South Carolina; Virginia.

Canada; Mexico; Cornwall, England; Portugal; Japan; China; New South Wales, Australia

Araca Mine, Bolivia: source of most of the gem material known: yellow, gray, colorless and light yellowish brown to reddish brown.

Spain: gem material in yellowish to red cuttable pieces.

Erongo tinfields, Namibia: gem material.

COMMENTS: Cassiterite has tremendous dispersive fire, much more than diamond, that is visible in properly cut pale-colored gems. This lighter-colored material is, however, very rare except in small fragments. Cassiterite is a fine gemstone – it is rather hard, and there is no cleavage problem. It is unfortunate that cuttable rough is so scarce. Cassiterites under 5 carats are not among the rarest of rare stones, but large clean gems definitely are.

NAME:  The Greek word for tin is kassiteros.