Chapmanite
| Synonyms: | Antimon-Hypochlorite, Hoeferite, Höferite |
| Classification: | Silicates, Phyllosilicates |
| Chemical formula: | Fe3+2Sb3+(SiO4)2(OH) |
| Crystal system: | Monoclinic |
| Density (g/cm3): |
3.69 - 3.75 measured, 4.29 calculated |
| Cleavage: | None |
| Fracture: | Irregular / uneven, conchoidal |
| Hardness (Mohs): | 2.5 |
| Colour: | Olive green to deep yellow |
| Lustre: | Dull, sub-vitreous, adamantine |
| Streak: | Yellowish green |
| Transparency: | Transparent |
| Type locality: | Keeley-Frontier Mine (Canadian Keeley; Frontier Mine; Keeley Mine), South Lorrain Township, Cobalt-Gowganda region, Timiskaming District, Ontario, Canada |