By Trtrtr (original) [Public domain], via Wikimedia Commons
This attractive but rather rare mineral has seldom been cut as a gemstone. Polished slabs and rough material appeared in 1986 at a mineral show in substantial quantities, however. This material is Mexican, translucent to opaque, and medium to dark purple in color.
| Data | Value |
|---|---|
| Name | Spurrite |
| Colors | Gray, lavender-gray, purple. |
| Crystallography | Monoclinic. Crystals anhedral; usually massive, granular. |
| Refractive Index | 1.640-1.679 |
| Luster | Vitreous. |
| Hardness | 5 |
| Fracture | Uneven to splintery |
| Specific Gravity | 3.0 |
| Birefringence | 0.039 |
| Cleavage | Distinct 1 direction |
| Luminescence | Not reported. |
| Luminescence Present | No |
| Transparency | Transparent to opaque. |
| Absorption Spectrum | Not reported. |
| Formula |
Ca5Si2O8CO3 |
| Pleochroism |
Not reported. |
| Optics |
a = 1.640; β = 1.674; γ = 1.679. Biaxial (-), 2V= 40°. |
| Optic Sign | Biaxial - |
Optics: a = 1.640; β= 1.674; γ=1.679.
Biaxial (-), 2V= 40°.
Occurrence: A contact mineral in limestones.
Crestmore, California; Tres Hermanes, New Mexico.
Scawt Hill, County Antrim, Ireland.
Velardena mining district, Durango, Mexico.
Comments: This attractive but rather rare mineral has seldom been cut as a gemstone. Polished slabs and rough material appeared in 1986 at a mineral show in substantial quantities, however. This material is Mexican, translucent to opaque, and medium to dark purple in color.
The hardness and tenacity are adequate for use as cabochons.
Name: After the American geologist, Josiah Edward Spurr.
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