Covellite is one of the most representative supergenic minerals related to porphyry copper, it is basically a copper sulfide that occurs with a striking indigo blue color and earthy habit. It is one of the most important sulfide minerals because it contributes as a secondary Ore mineral in the extraction or exploitation of copper worldwide.
Physical and chemical properties
The most relevant physical and chemical properties of this mineral are presented below.
| Covellite | Physical and chemical properties |
|---|---|
| Class, group | sulphide, copper sulphide |
| Chemical composition | Copper (Cu)(66.46%) and Sulfur (S)(33.54%) |
| Chemical formula | CuS |
| Color | characteristic indigo blue |
| Mohs hardness | 1 to 1.5 |
| Density or Specific Weight | 4.6 to 4.7 gr/cm3 |
| stripe color | Gunmetal to Metallic Black |
| Brightness | Earthy, resinous, submetallic |
| crystalline system | Hexagonal |
| Fracture | Perfect, in leaves or micácea |
| Habit | Massive, leafy, granular and earthy aggregates |
| Exfoliation or cleavage | Perfect |
| Impurities | Silver, iron, selenium, lead |
| Transparency | Opaque |
| formation temperature | Less than 150°C |
| Paragenesis | Bornite, Chalcopyrite, Chalcocite, Pyrite, Enargite, Tetrahedrite, Cacosine |
| Source | Secondary, oxidation and hydrothermal |
| Applications | copper ore, collectibles |
Characteristics of covellite
This mineral is characterized because it appears with a striking indigo blue color, in addition soft is usually earthy, resinous, or submetallic. Regarding its chemical composition, it contains around 66.46% copper and 33.54% sulfur, which is why it is considered a copper sulfide, its chemical formula is CuS.
Its hardness is generally low, a typical characteristic of almost all sulfides, it is usually around 1.5 to 2 on the Mohs scale. Its density or specific weight is considered intermediate and varies in the range of 4.6 to 4.7 grams per cubic centimeter.
The covelline crystallizes in the hexagonal crystal system. Its origin is mainly secondary hydrothermal due to the oxidation of chalcopyrite, so it is very common to find it enriching the sulfide zone of mineral deposits related to copper.
Visually it is very similar to bornite, however, bornite is harder and is characterized by being iridescent.
Origin, formation, genesis
It is characterized by the fact that it forms in supergenic (supergenic) or exogenous zones, therefore it is common for it to originate due to the oxidation or alteration of a primary mineral, in this case chalcopyrite or bornite.
Therefore, if large concentrations of covellite are found, it is generally associated with the fact that, far below this mineral, there are large concentrations of chalcopyrite and bornite, which are the primary minerals in the extraction of copper.
It is also associated with other minerals such as limonite, hematite, ocher, and chalcocite.
Associated mineral deposits
It is typically associated with supergenic deposits that have been formed by the alteration of other types of primary deposits such as porphyry copper through oxidation and leaching processes.
So it is very common to find this mineral forming part of areas highly rich in secondary minerals very close to the surface of the earth or soil.
Identification of the covellite
The covellite It is characterized because it appears with an earthy and leafy habit, it has a low Mohs hardness of 1.5 to 2, its characteristic color is indigo blue and above all it must be taken into account that the covelline Stains hands to the touch with a metallic dark gray color.
Due to its color, its low hardness, the way in which it appears, covelline is often confused with thebornita, with the molbdeniteand sometimes with chalcocite, however it must be taken into account that bornite is an iridescent mineral and has greater hardness, molybdenite, on the other hand, has a color similar to aluminum foil, while chalcocite (chalcocite) is steel-colored silver and also has greater hardness.
Below is a diagram that serves to differentiate some similar metallic minerals, including covellite.
Uses of covellite
- To covellite It is considered an important copper ore, that is to say that this valuable metal can be extracted from this mineral. Let us remember that this mineral contains around 66.46% copper, which makes it very attractive to mining companies.
- Geologists use the covellite as an exploration guide for the search for porphyry copper deposits and sometimes veins or hydrothermal veins, through the interpretation of copper geochemical anomalies.
- Finally, due to its very striking indigo blue color, many people collect this mineral (collecting).