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 |
| Formula | Ca5Si2O8CO3 |
| Colors | Gray, lavender-gray, purple. |
| Fracture | Uneven to splintery |
| Hardness | 5 |
| Cleavage | Distinct 1 direction |
| Crystallography | Monoclinic. Crystals anhedral; usually massive, granular. |
| Refractive Index | 1.640-1.679 |
| Birefringence | 0.039 |
| Luminescence | Not reported. |
| Luminescence Present | No |
| Absorption Spectrum | Not reported. |
| Pleochroism | Not reported. |
| Optics | a = 1.640; β = 1.674; γ = 1.679. Biaxial (-), 2V= 40°. |
| Optic Sign | Biaxial - |
| Luster | Vitreous. |
| Specific Gravity | 3.0 |
| Transparency | Transparent to opaque. |
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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