Colemanite
Colemanite is just a gem that is unusual is maybe not particularly appealing but is really a rarity for collectors. Colemanite is a treasure that is interesting that it’s pyroelectric and piezoelectric at very low conditions. Colemanite is also fluorescent showing bright pale under that is yellow and longwave UV that can phosphoresce pale green. Gems have become difficult to facet since Colemanite is fragile and brittle with perfect cleavage in one single direction and it is really slightly soluble in water.
Colemanite is really a borate that is complex, and like other borates, it is found in playa lakes and other evaporite deposits. Colemanite can be an ore of boron and a way to obtain borax that is a cleansing agent and of good use chemical that is industrial.
Current resources of Colemanite are Yermo, Boron, Death Valley and other Ca localities, USA; Chile; and Panderma, Turkey.
| Category: | Inoborates |
| Chemical Formula: | Ca2B6O11 · 5(H2O) |
| Hydrated Calcium Borate | |
| Molecular Weight: | 411.09 gm |
| Composition: | Calcium | 19.50 % | Ca | 27.28 % | CaO |
| Boron | 15.78 % | B | 50.81 % | B2O3 | |
| Hydrogen | 2.45 % | H | 21.91 % | H2O | |
| Oxygen | 62.27 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | As equant to short prismatic crystals, with large and multiple terminating forms, to 30 cm; pseudorhombohedral and pseudo-octahedral; nearly 50 forms measured; cleavable massive, granular, most commonly nodular. |
| Twinning: | None |
| Cleavage: | Perfect on [010], Distinct on [001] |
| Fracture: | Irregular/Uneven to Sub-Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 4.5 |
| Density: | 2.423 (g/cm3) |
| Luminescence: | Fluorescent; bright pale yellow under SW UV and LW UV. May phosphoresce pale green. |
| Radioactivity: | Not Radioactive |
| Other: | Pyroelectric and Piezoelectric at very low temperatures. Very slightly soluble in water (1 part in 1,100 at 20°-25°) |
| Color: | Colorless, gray, gray white, yellowish white, white |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous to Adamantine |
| Refractive Index: | 1.586 – 1.614 Biaxial ( + ) |
| Birefringence: | 0.0280 |
| Dispersion: | Relatively weak; r > v |
| Pleochroism: | None |
