Bementite
Bementite is a rare Silicate that is manganese mineral is available as radiated or stellate crystals to massive granular forms and often found in intricate intergrowths with other minerals.
Bementite localities come in the USA, at Franklin, Sussex County, New Jersey; in Washington, in the Olympic Peninsula, an ore mineral at a real number of small deposits in Clallan, Jefferson, and Mason Counties; from Ray, Pinal County, Arizona; at Hale Creek, Trinity County, California; and from the Black Diablo mine, Black Diablo district, Pershing County, Nevada. In the Treburland mine, Altarnun, Cornwall, and near Chillaten, Devon, England. From Langbån, Värmland, Sweden. In Russia, at a real number of poorly-defined localities. In the Tokuzawa mine, Fukushima Prefecture; the Ichinomata mine, Kumamoto Prefecture; and at Kunimiyama, Kochi Prefecture, Japan. Into the Wessels mine, near Kuruman, Cape Province, South Africa.
| Chemical Formula: | Mn5Si4O10(OH)6 |
| Manganese Silicate Hydroxide | |
| Molecular Weight: | 1,018.08 gm |
| Composition: | Manganese | 43.17 % | Mn | 55.74 % | MnO |
| Silicon | 16.55 % | Si | 35.41 % | SiO2 | |
| Hydrogen | 0.99 % | H | 8.85 % | H2O | |
| Oxygen | 39.29 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | Radiated or stellate with minute foliated structure; compact, hornlike forms; massive granular; in intricate intergrowths with other minerals. |
| Twinning: | None |
| Cleavage: | Perfect on {001}, very Good on {100} and {010} |
| Fracture: | Conchoidal |
| Tenacity: | Flexible |
| Moh’s Hardness: | 6.0; Sometimes given as variable 4-6, softer mineral due to alteration. |
| Density: | 2.90 – 3.10 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Brown, Dark Drown, Golden Brown, Grayish-Yellow |
| Transparency: | Translucent to Sub-Translucent |
| Luster: | Sub-Vitreous, Resinous, Greasy, Pearly on perfect cleavage |
| Refractive Index: | 1.602 – 1.650 Biaxial ( – ) |
| Birefringence: | 0.026 – 0.030 |
| Dispersion: | Weak |
| Pleochroism: | Weak; colorless, pale yellow |
