Pyrolusite owes its name to a combination of words from the Greek “Pyr” fire “Louein” to wash, because this mineral was once used as the main chemical agent in the removal of green and brown tints in the manufacture of glass.
What is pyrolusite?
Pyrolusite is a mineral that belongs to the group of oxides and is specifically an oxide of manganese. It typically presents as a dark gray to black color and sometimes with a bluish cast.
It is a very striking mineral because it can occur in a fibrous, needle-like crystalline form that can stain the hands to the touch. But it also usually appears with spectacular tree forms on top of rocks or filling in spaces in rocks.
Properties and characteristics of pyrolusite
Pyrolusite is a mineral that has the chemical formula MnO2, for this reason it is considered a manganese dioxide. On the Mohs hardness scale, its value is from 6 to 6.5, however, it is quite reactive and does not resist environmental conditions very well, so its hardness seems to be lower.
It is identified by its dark gray and bluish-black color and by the fact that it appears in thin and sharp crystals, the same ones that are usually striated. In addition, it can be a secondary mineral and in this case it usually has arborescent forms impregnated on top of the rocks and filling in spaces.
| pyrolusite | Physical and chemical properties |
|---|---|
| Chemical formula | MnO2 |
| class, group | oxides |
| Composition | manganese dioxide |
| Color | Dark gray to black, sometimes with a bluish tinge |
| Stripe | bluish black to black |
| Mohs hardness | 6 – 6.5 |
| crystalline system | tetragonal |
| Transparency | Opaque |
| specific gravity | 4.4 – 5 |
| Gloss | metallic, opaque |
| Neckline | 1.1 |
| Fracture | chipped,uneven |
| Tenacity | Fragile |
| Other identification marks | Leaves a black powdery residue on contact with surfaces. |
| Most striking features | Crystalline habits, veins and dusty residuals |
| Ambient | In the oxidized zone of hydrothermal replacement deposits and in acid-rich peatlands as a product of alteration. |
Origin and geological environment
Pyrolusite belongs to both a primary environment and a secondary environment. Primary pyrolusite is related to hydrothermalism and corresponds to crystallized minerals. It is generated at a low temperature of about 250°C.
While secondary pyrolusite occurs in oxidation zones and as hydrothermal replacements for oxide minerals in manganese-rich rocks. It is very common to find it in areas affected by groundwater and surface water.
Pyrolusite deposits
Manganese ores, mainly pyrolusite (MnO2), are mined in South Africa, but there are smaller deposits in Australia, China, Brazil, India, Ukraine, and some African and Asian states.
Most of the manganese extracted from pyrolusite is used, for its anticorrosion properties, in iron or aluminum alloys. Other uses include as a cathode in some batteries and as a pigment.
Uses of pyrolusite
Throughout history, pyrolusite has had several important uses that are listed below:
General uses
- It is an ore of manganese : Because pyrolusite is an oxide of manganese, this chemical element is extracted from it, which has several industrial and pharmaceutical applications.
- Steel component and batteries : Due to its chemistry, this mineral is used as a component in the manufacture of steel and as a component in electric batteries for cars and cell phones.
- It is also used in the preparation of chlorine and as an agent in blue-black dyes and dyes or pigments.
Uses as ornamental stone
Pyrolusite is a very striking and beautiful mineral, in fact, many mineral collectors look for it in order to enhance their collection. This mineral appears in very varied forms which makes it more attractive.