Pyroxene minerals are known beyond Earth. They are abundant in many stone meteorites and present in some stony-iron meteorites. They have also been identified in the rocks and regolith of the Moon and Mars.
When compared to terrestrial rocks, rocks of the Moon and Mars have simple mineral compositions. This is because they have not been significantly altered by chemical weathering. Their composition is dominated by plagioclase feldspar and pyroxene minerals.
| Physical Properties of Pyroxenes | |
| Chemical Classification | Silicate |
| Color | Usually dark green to dark brown or black. Some, such as jadeite and spodumene, occur in a range of colors. |
| Streak | White |
| Luster | Vitreous to dull |
| Diaphaneity | Semi-translucent to opaque |
| Cleavage | Most pyroxene minerals exhibit two directions of cleavage that intersect at approximately 87o and 93o. Cleavage fragments often have a nearly square cross-section. |
| Mohs Hardness | 5 to 7 |
| Specific Gravity | 3 to 4 |
| Diagnostic Properties | Stubby prismatic crystals. Angle of cleavage plane intersection. |
| Chemical Composition | A generalized composition of XYZ2O6, as described in the accompanying sections. |
| Crystal System | Monoclinic or orthorhombic |
| Uses | Most pyroxenes have no regular use as industrial minerals. Pyroxene minerals are minor to secondary components of some rocks that are used as crushed stone and dimension stone. A few pyroxene minerals are used as gem materials, but only in rare instances when they have attractive color and clarity. Jadeite, diopside, and spodumene are the most important pyroxene gem materials. Spodumene was once an important source of lithium. |