Minerals in Space: Extraterrestrial Mineralogy

## Beyond Earth's Minerals

The study of extraterrestrial minerals reveals how geological processes work without water, atmosphere, or plate tectonics. Some minerals found in meteorites and on other worlds do not exist naturally on Earth.

## Meteorite Minerals

### Iron Meteorites

| Mineral | Formula | Crystal System | Significance |
|---------|---------|----------------|-------------|
| Kamacite | α-(Fe,Ni) | Cubic (BCC) | Low-Ni iron (5–7% Ni) |
| Taenite | γ-(Fe,Ni) | Cubic (FCC) | High-Ni iron (20–65% Ni) |
| Schreibersite | (Fe,Ni)₃P | Tetragonal | Source of prebiotic phosphorus |
| Troilite | FeS | Hexagonal | Iron sulfide (not found naturally on Earth) |

The Widmanstätten pattern in iron meteorites is formed by the intergrowth of kamacite and taenite during extremely slow cooling (1–10°C per million years) in the cores of asteroids.

### Stony Meteorites (Chondrites)

| Mineral | Formula | Mohs | Significance |
|---------|---------|------|-------------|
| Olivine | (Mg,Fe)₂SiO₄ | 6.5–7 | Most common mineral in chondrites |
| Pyroxene (enstatite) | MgSiO₃ | 5.5 | High-Mg variety dominant |
| Plagioclase | (Na,Ca)(Al,Si)₄O₈ | 6–6.5 | Feldspar in achondrites |
| Chromite | FeCr₂O₄ | 5.5 | Survives weathering, used to find meteorites |

### Unique Meteorite Minerals

Over 60 mineral species have been first discovered in meteorites:

| Mineral | Formula | Found In | Earth Occurrence |
|---------|---------|----------|------------------|
| Ringwoodite | (Mg,Fe)₂SiO₄ (spinel structure) | Shocked meteorites | Earth's mantle (660 km) |
| Bridgmanite | (Mg,Fe)SiO₃ (perovskite structure) | Shocked meteorites | Earth's lower mantle |
| Oldhamite | CaS | Enstatite chondrites | Does not occur on Earth's surface |
| Daubreelite | FeCr₂S₄ | Iron meteorites | Extremely rare on Earth |

## Lunar Minerals

### Apollo Sample Findings

| Mineral | Formula | Abundance | Notes |
|---------|---------|-----------|-------|
| Plagioclase (anorthite) | CaAl₂Si₂O₈ | Dominant in highlands | The Moon's crust is >90% anorthite |
| Pyroxene | (Ca,Mg,Fe)SiO₃ | Major in mare basalts | Augite and pigeonite |
| Olivine | (Mg,Fe)₂SiO₄ | Common | Mg-rich varieties |
| Ilmenite | FeTiO₃ | Significant in mare | Source of oxygen for future bases |
| Armalcolite | (Mg,Fe)Ti₂O₅ | Rare | Named for **Arm**strong, **Al**drin, **Col**lins |

## Martian Minerals

Mars rovers and orbiters have identified minerals that reveal the planet's wet past:

- **Hematite** (Fe₂O₃): "Blueberry" concretions at Meridiani Planum — formed in water
- **Jarosite** (KFe₃(SO₄)₂(OH)₆): Acidic water indicator
- **Gypsum** (CaSO₄·2H₂O): Veins in Gale Crater — precipitated from groundwater
- **Olivine**: Extensive in Nili Fossae — minimal weathering (dry conditions)

## Asteroid Mining Potential

| Asteroid Type | Mineral Content | Economic Interest |
|---------------|----------------|-------------------|
| C-type (carbonaceous) | Phyllosilicates, organics, water ice | Water, volatiles |
| S-type (stony) | Olivine, pyroxene, Fe-Ni metal | Platinum group elements |
| M-type (metallic) | Kamacite, taenite | Iron, nickel, cobalt, platinum |