Högbomite
Högbomite was originally described by Axel Olof Gavelin in 1916 from material found at Ruoutevare, Kvikkjokk, Lappland, Sweden. It was named by Gavelin in honor of Arvid Gustav Högbom (1857-1940), teacher of geology and mineralogy, University of Uppsala, Sweden. Högbomite was renamed Magnesiohögbomite-2N2S in 2002 based on the högbomite that is brand new nomenclature approved by the IMA CNMMN (Commission on New Minerals and Mineral Names). Högbomite has become a group name comprised of seven members of similar chemistry but various elements which are dominant. The 2N2S relates to 2 Nolanite and 2 Spinel modules in its chemistry. The name Högbomite is additionally used synonymously with unspecified members of this Högbomite Group. Högbomite is weakly magnetic, black and opaque with adamantine luster and often intergrown with Ilmenite and Pleonaste.
Högbomite distribution: in the Ruoutevare Fe–Ti deposit, near Kvikkjokk, Norrbotten, Sweden. At Rödstrand, Norway. From the Shoriya Mountains, western Siberia, Russia. At Cashal, near Toombeola, County Galway, Ireland. On Mautia Hill, Tanzania. At the Linganga deposit, Njombe district, Tanzania. From Tsaobis, Namibia. In the USA at Whittles, Pittsylvania County, Virginia; Peekskill, Westchester County, New York; and Franklin, Macon County, North Carolina. In the Romay mine, San Juan, Catamarca Province, Argentina. From the Strangways Range, Northern Territory, Australia. On the Prince Olav Coast, eastern Antarctica. More localities axe known.
| Chemical Formula: | (Mg,Fe2+)2(Al,Ti)5O10 |
| Magnesium Iron Aluminum Titanium Oxide | |
| Molecular Weight: | 423.03 gm |
| Composition: | Magnesium | 3.45 % | Mg | 5.72 % | MgO |
| Titanium | 3.40 % | Ti | 5.66 % | TiO2 | |
| Aluminum | 31.89 % | Al | 60.26 % | Al2O3 | |
| Zinc | 3.09 % | Zn | 3.85 % | ZnO | |
| Iron | 17.16 % | Fe | 16.98 % | FeO / 5.66 % Fe2O3 | |
| Hydrogen | 0.17 % | H | 1.49 % | H2O | |
| Oxygen | 40.85 % | O | |||
| 100.00 % | 99.62 % | = TOTAL OXIDE |
| Crystallography: | Hexagonal – Dihexagonal Pyramidal |
| Crystal Habit: | Rare crystals are tabular, thin to thick, on {0001}, to 5 mm; commonly granular, massive, intergrown and included with other species. |
| Twinning: | On {0001}, may be repeated; on {h0hl}, probable |
| Cleavage: | Imperfect on {0001}, another on {h0hl}, may be partings |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.5; Vickers: VHN100=1064 – 1216 kg/mm2 |
| Density: | 3.81 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Weakly magnetic |
| Color: | Black; brown in transmitted light; gray in reflected light |
| Transparency: | Opaque, transparent in thin fragments |
| Luster: | Adamantine |
| Refractive Index: | 1.803 – 1.853 Uniaxial ( – ) |
| Birefringence: | 0.030 – 0.045 |
| Dispersion: | n/a |
| Pleochroism: | Distinct; O = dark golden brown; E = light golden brown |
| Anisotropism: | Distinct |
