Hopeite
Hopeite is a rare zinc phosphate mineral that is rarely available as a gem that is faceted. The locality that is gemmy crystals is Kabwe (Broken Hill), Central Province, Zambia. Crystals from this location can be very well appealing and formed in shades of brownish orange to orange but are particularly small. Hopeite is dimorphous with the mineral parahopeite. The two have the exact chemistry that is exact same different structures. Hopeite is orthorhombic and parahopeite is triclinic.
Hopeite is available at Vieille Montagne (Altenberg), Moresnet district, Belgium. In Germany, at Bad Ems, Rhineland-Palatinate; from Hagendorf, Bavaria; and at Oberschulenberg, Harz Mountains. Relatively large crystals at Kabwe (Broken Hill), Zambia. From the Hudson Bay mine, about eight km southeast of Salmo, British Columbia, Canada. In America, at the Tip Top mine, 8.5 kilometer southwest of Custer, Custer County, South Dakota; through the Palermo number 1 mine, near North Groton, Grafton County, New Hampshire; and within the Iron Cap Pb–Zn mine, near Aravaipa, Graham County, Arizona.
| Category: | Phosphate minerals |
| Chemical Formula: | Zn3(PO4)2•4(H2O) |
| Hydrated Zinc Phosphate | |
| Molecular Weight: | 458.17 gm |
| Composition: | Zinc | 42.82 % | Zn | 53.29 % | ZnO |
| Phosphorus | 13.52 % | P | 30.98 % | P2O5 | |
| Hydrogen | 1.76 % | H | 15.73 % | H2O | |
| Oxygen | 41.90 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | Crystals tabular {010} to prismatic [001], and occurring individually or as tufted or divergent aggregates and crusts. Face development is frequently irregular. The crystals may simulate disphenoidal or hemimorphic symmetry. Reniform masses; compact. |
| Twinning: | None observed |
| Cleavage: | Perfect on {010}; good on {100}; poor on {001} |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 3.5 |
| Density: | 3.00 – 3.10 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Readily soluble in dilute HCl. |
| Color: | Colorless, Grayish White, pale Yellow, Brownish Orange; Colorless in transmitted light. |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous, Pearly on {010} cleavages |
| Refractive Index: | 1.572 – 1.592 Biaxial ( – ); sections || {100} are optically sectorially zoned. |
| Birefringence: | 0.018 |
| Dispersion: | Perceptible; r < v |
| Pleochroism: | None |
