Aramayoite
Ag3Sb2(Bi,Sb)S6 [CNMNC approved formula]
Named for Felix Avelino Aramayo, former Managing Director of the Compagnie Aramayo de Mines en Bolivie.
| IMA status : | Valid species (Pre-IMA 1926) Grandfathered |
| CLASSIFICATION | |
| Dana (8th edition) : |
03.07.04.01 |
| (03) Sulfides - Sulfosalts | |
| (03.07) where z/y = 2 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals | |
| (03.07.04) | |
| Nickel-Strunz (10th edition) : |
02.HA.25 |
| (02) Sulfides | |
| (02.H) Sulfosalts of SnS Archetype | |
| (02.HA) With Cu, Ag, Fe (without Pb) | |
| Crystal system: | Triclinic System |
| Point group (H-M): | 1 — pinacoidal |
| Unit cell: | a = 7.74Å, b = 8.84Å, c = 8.32Å α = 100.7°, β = 90°, γ = 103.9° |
| Crystal Habit: | Aggregates thin broad plates parallel to (010), striated along {100} and {001} |
| Twinning: | about [101] with the composition plane near {101} |
| Color: | Iron-black |
| Diaphaneity: | Nearly opaque |
| Luster: | Metallic |
| Hardness (Mohs): | 2.5 |
| Measured Density: | 5.60 g/cm3 |
| Cleavage: | 3; {010} perfect, {100} fair, {001} poor |
| Tenacity: | Sectile, thin flakes are flexible but not elastic. |
| Streak: | Black to red-brown |
| Geologic Setting: | Rare, typically in vein-controlled hydrothermal Sn–Ag ores. |
| Mineral Association: | Tetrahedrite, miargyrite, stannite, pyrite, quartz |
Aramayoite is present as large thin plates (blue iridescence) to 1mm in photo. Miargyrite is present as equant, blocky crystals to 1mm.Origin: Julcani Silver mine, Huancavelica Dept., Peru
Sample size: 2.5 x 1.5 x 1.5 cm
Photo: Tom Loomis
(zoom-in of above)