Phosphosiderite
Phosphosiderite is a rare mineral found as minute crystals of pink or red. The chemical formula of Phosphosiderite is FePO4 • 2(H2O) (Hydrated Iron Phosphate) and its molecular weight is 186.85 gm. It is also found as massive or botryoidal forms suitable for cabochons. Phosphosiderite has a specific gravity of 2.74 – 2.76 (g/cm3) and the refractive index of 1.692 – 1.738 Biaxial ( – ). Phosphosiderite is similar in appearance to Sugilite. The pink, opaque massive material is currently being mined in Chile. This material is either solid pink, lavender or purple and may have yellow veins. It is also known as “piedra voga” (pink stone) as well as “la rosa vocal” (punk rock).
| Chemical Formula: | FePO4 • 2(H2O) |
| Hydrated Iron Phosphate | |
| Molecular Weight: | 186.85 gm |
| Composition: | Iron | 29.89 % | Fe | 42.73 % | Fe2O3 |
| Phosphorus | 16.58 % | P | 37.98 % | P2O5 | |
| Hydrogen | 2.16 % | H | 19.28 % | H2O | |
| Oxygen | 51.38 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | Crystals tabular {010} or stout prismatic [001]. Also occurs as botryoidal or reniform masses and crusts with a radial-fibrous structure. |
| Twinning: | On {101}, common, typically as interpenetrations |
| Cleavage: | Distinc/good on {010}, Indistinct on {001} |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 3.5 – 4.0 |
| Density: | 2.74 – 2.76 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Totally soluble in HCl, nearly insoluble in HNO3 |
| Color: | Colorless, purple, pink, red, red violet |
| Transparency: | Transparent to Translucent, Opaque |
| Luster: | Vitreous to Sub-Resinous |
| Refractive Index: | 1.692 – 1.738 Biaxial ( – ) |
| Birefringence: | 0.046 |
| Dispersion: | Very strong; r > v |
| Pleochroism: | Visible; X = pale rose-red; Y = carmine-red; Z = colorless |
