Highest values go to finer blue colors.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Orthorhombic. Crystals slender prismatic; massive, granular; fibrous.|
|Colors||Blue of various shades.|
|Luster||Vitreous to silky.|
|Polish Luster||Vitreous to silky|
|Fracture Luster||Uneven to splintery|
|Cleavage||Very good in 2 directions. Fracture uneven to splintery.|
|Stone Sizes||Only cabochons can be cut, up to several inches in length.|
|Absorption Spectrum||Not diagnostic|
a = 1.752-1.753; β= 1.782; γ=1.815. Mean refractive index 1.75.
Biaxial (+), 2V: 88°.
An alteration product of secondary copper minerals.
- Shattuck Mine, Bisbee, Arizona: dense blue massive material; also psuedomorphous after malachite.
- Ajo, Arizona: with other copper minerals.
- Katanga, Zaire: masses of light blue crystals; fibrous, radial aggregates, sometimes resembling a pale blue pectolite.
Comments by Dr. Joel Arem
Shattuckite is often mixed with quartz, and data often reported for properties may be erroneous. The cabochons are rich blue in color and very popular, but the material is not abundant and seldom seen on the market.
Comments by Donald Clark, CSM IMG
Often mixed with quartz. Primary source Shattuck Mine, Bisbee Arizona.
Shattuckite is often confused with plancheite, which has recently been identified as a separate species, formula Cu8(Si4O11)2(OH)4 . xH20 There is no method of distinguishing between these species with common instruments. Gems must be sent to a major lab for positive identification.
From the Arizona locality, the Shattuck Mine. Recent studies have shown that plancheite, a mineral similar to and often confused with shattuckite, is a distinct species. The formula of plancheite is: Cu8(Si4O11)2(OH)4 ·Xh2O.