Massive hemimorphite can have a very delicate, blue color. However, it's seldom cut because not very much has appeared on the market.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Orthorhombic. Crystals tabular and thin, striated; fan-shaped aggregates.|
|Colors||White, colorless, pale blue, greenish, gray, yellowish, brown.|
|Luster||Vitreous, silky; dull.|
|Fracture||Even to subconchoidal. Brittle.|
|Cleavage||Perfect 1 direction.|
|Luminescence||Weak blueish fluorescence under SW UV.|
|Transparency||Transparent to opaque|
|Optics||a = 1.614; β = 1.617; γ = 1.636. Biaxial (+), 2V= 46°.|
|Etymology||From the Greek hemi and morphe, meaning “half-form,” in allusion to its crystal form.|
|Occurrence||A secondary mineral in the oxide zones of ore deposits.|
In the early 19th century, the British mineralogist James Smithson discovered that the zinc ore then known as calamine was composed of hemimorphite and smithsonite. These minerals, along with hydrozincite, are, in fact, distinct minerals despite their external similarities.
As crystals, hemimorphites show different terminations at each end. Hence the name hemi – morphite, since each end or “half” takes a different “form.”
This gem exhibits the pyroelectric effect. When heated, it generates an electrical charge.
Natural gems such as smithsonite, chrysocolla, and turquoise may also resemble hemimorphite. However, these gems possess very different properties and should be distinguished easily. Chrysocolla’s and turquoise’s specific gravities differ significantly from hemimorphite’s. Smithsonite’s specific gravity and optic sign also differ from those of its former partner in calamine.
In Mexico, Mapimi, Durango and Santa Eulalia, Chihuahua produce crystals up to several inches in length. Some of these are transparent and yield stones up to approximately 7 – 10 carats. Blue crusts are also found. Other Mexican locations produce beautiful gems as well.
This mineral is found in various localities worldwide. Other notable gem-quality sources include:
- United States: southwestern states.
- China; Democratic Republic of the Congo; Republic of the Congo; Italy.
Gem cutters have cut cabochons up to several inches in length from massive blue material. They’ve also faceted colorless material from Mexico into gems from 1 – 3 carats in size. Larger stones are very rare.
- Devonian Group (Calgary, Alberta, Canada): 1.90 (colorless, Mexico).
Due to their relatively low hardness, store these gems separately from other harder, more common jewelry stones, such as quartz. For cleaning, use a soft brush, mild detergent, and warm water only. Consult our gemstone jewelry cleaning guide for more recommendations.