Meyerhofferite
Meyerhofferite is a hydrated borate mineral. It occurs principally as an alteration product of Inyoite, another borate mineral. Meyerhofferite is rarely cut as a gem because it is very soft, has perfect cleavage and since crystals are very rarely large enough or clean enough. Gems are an oddity for collectors of the rare and unusual.
Natural Meyerhofferite was discovered in 1914 in Death Valley, California. It is named for German chemist Wilhelm Meyerhoffer (1864-1906), collaborator with J. H. van’t Hoff on the composition and origin of saline minerals, who first synthesized the compound.
Distribution of Meyerhofferite is in the USA, from the Mt. Blanco deposit and along Gower Gulch, Furnace Creek district, Death Valley, Inyo County, and in the Kramer Borate deposit, Boron, Kern County, California. At Mesa del Almo, 13 km southeast of Magdalena, Sonora, Mexico. In Argentina, at the Anita mine, Sijes district, and in the Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province. In Turkey, from many deposits in the Bigadiç borate district, Balikesir Province; in the Killik and Espey borate mines, near Emet, Kütahya Province. At the Inder borate deposit, Kazakhstan.
| Category: | Nesoborates |
| Chemical Formula: | Ca2B6O6(OH)10•2(H2O) |
| Hydrated Calcium Borate Hydroxide | |
| Molecular Weight: | 447.12 gm |
| Composition: | Calcium | 17.93 % | Ca | 25.08 % | CaO |
| Boron | 14.51 % | B | 46.71 % | B2O3 | |
| Hydrogen | 3.16 % | H | 28.20 % | H2O | |
| Oxygen | 64.41 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Rare as complex acicular to crude crystals, to 4 cm, in fibrous divergent, radiating aggregates, commonly reticulated; may be nodular. |
| Twinning: | None |
| Cleavage: | On {010} Perfect; in traces on {100} and {110} |
| Fracture: | Conchoidal to Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 2.0 |
| Density: | 2.120 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Readily soluble in acids. |
| Color: | Colorless to White, pale Yellow |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous to Silky |
| Refractive Index: | 1.500 – 1.560 Biaxial ( – ) |
| Birefringence: | 0.060 |
| Dispersion: | Relatively Weak; r > v |
| Pleochroism: | None |
