Acanthite is one of the most important sulphide minerals because it is enriched in silver, therefore it is a silver sulphide. It contains in its chemical composition around 87.06% silver and 12.94% sulfur, it also contains selenium impurities, its chemical formula is (Ag2S).
Physical and chemical properties of acanthite
| Acanthite | Physical and chemical properties |
|---|---|
| group, class | Sulfide – silver sulfide |
| Chemical composition | Silver (Ag) (87.06%) and sulfur (S) (12.94%) |
| Chemical formula | Ag2S |
| Impurities | selenium, iron |
| Color | dark grey, lead, black |
| stripe color | Glossy or metallic black |
| Mohs hardness | two |
| Density or Specific Weight | 7.2 to 7.4 |
| Fracture | conchoidal or uneven |
| Tenacity | sectile, flexible |
| Exfoliation | imperfect |
| Brightness | Shiny metallic (goes dull in light) |
| Transparency | Opaque |
| Morphology | Crystals, granular aggregates, massive, pseudomorphs. |
| Habit silver | Octahedrons, hexahedrons, dodecahedrons. |
| Habit acanthita | Tabular, columnar, faces often curved and uneven, pseudomorphs. |
| Malleability | If you present |
| formation temperature | 100°C to 200°C |
| crystalline system | Monoclinic at room temperature and cubic at more than 179 °C. |
| Applications | Important ore of silver. |
Characteristics of the acanthite
This sulfur is characterized by the fact that it usually occurs in dark gray promos and black colors, in addition to having a characteristic brilliant metallic luster that becomes matt with exposure to light.
The form in which it usually appears is crystalline.
The crystal system of the silver or acanthite is dimorphic, this means that it depends on the pressure and temperature to appear from one other crystalline system.
The cliff At atmospheric pressure and temperature it usually occurs in the monoclinic crystalline system, while the variety silver It always occurs in the cubic crystalline system when it exceeds 179 degrees Celsius of formation.
Argentina or cliff It is also usually identified due to its semi-glossy black stripe color, in addition to the fact that its hardness on the Mohs scale is low, being 2.
Finally we can mention that its density or specific weight is in the range of 7.2 to 7.4, which is considered relatively high due to the silver content in its composition.
Origin, formation or genesis
The silver or cliff It is a mineral of secondary hydrothermal origin that typically occurs at temperatures between 100 to 200 degrees Celsius in hydrothermal fluid.
It is also associated with the minerals polybasite, silver, proustite, pyrargyrite, stephanite, sometimes with galena and calcite.
Associated mineral deposits
As for the mineral deposits associated with the silver or acanthite these occur mainly in hydrothermal deposits.
Due to the fact that it is associated with low formation temperatures, this mineral specifically occurs in low sulphidation thermal foot deposits, generally as electrum gold, that is, a mixture or natural alloy of gold and silver.
Also important quantities about not running in VMS deposits or volcanogenic massive sulphides.
Identification of the acanthite
This mineral almost never appears in large crystal sizes, so a geologist’s magnifying glass is very necessary for its identification.
Generally, it usually appears as granular and massive aggregate crystals, pseudomorphs.
Its natural gunmetal color must be distinguished and because its brilliant metallic luster becomes dull or matt in light.
The typical, like several types of sulfides that its hardness is low and its density is relatively high, the hardness on the Mohs scale is around 2.
Uses
Its main use is as the main silver ore, that is to say that the cliff either silver is used for the extraction of this valuable metal.
Secondarily, silver has important uses in the electronics industry, jewelry, medicine and various household activities.
Silver is part of various electronic components, our cell phones, solar panels, silver wires are also built to transmit electricity, silver coins and jewelry.
For geologists, this mineral is often used as a geological thermometer to define the low-temperature epithermal system.