How to Clean Minerals Safely

## The Golden Rule

Identify your mineral before cleaning it. A method that works perfectly on quartz can destroy a calcite specimen in seconds. Always test any cleaning method on an inconspicuous area first.

## Cleaning Methods by Mineral Group

### Water-Safe Minerals (Most Silicates and Oxides)

Minerals like quartz (SiO₂, Mohs 7), garnet, tourmaline, and corundum (Al₂O₃, Mohs 9) can be cleaned with warm water, mild dish soap, and a soft toothbrush.

### Iron Stain Removal

Iron oxide staining on quartz is extremely common. Treatment options:

| Method | Chemical | Duration | Best For |
|--------|----------|----------|----------|
| Oxalic acid | H₂C₂O₄ | 24–72 hours | Light to moderate staining |
| Iron Out (sodium dithionite) | Na₂S₂O₄ | 12–24 hours | Moderate staining |
| Sodium hydrosulfite soak | Na₂S₂O₄ | 1–7 days | Heavy staining |

**Safety**: Wear gloves and eye protection. Work in a ventilated area. Dispose of solutions properly.

### Acid-Sensitive Minerals (Carbonates)

Never use acid on these minerals — they will dissolve:

- Calcite (CaCO₃, Mohs 3) — fizzes in dilute HCl
- Dolomite (CaMg(CO₃)₂, Mohs 3.5–4)
- Rhodochrosite (MnCO₃, Mohs 3.5–4)
- Malachite (Cu₂(CO₃)(OH)₂, Mohs 3.5–4)
- Azurite (Cu₃(CO₃)₂(OH)₂, Mohs 3.5–4)

Clean carbonates with distilled water and a soft brush only. For stubborn clay, soak in water for several days.

### Water-Soluble Minerals

Never use water on:

- Halite (NaCl, Mohs 2.5) — dissolves immediately
- Sylvite (KCl, Mohs 2)
- Some sulfates: chalcanthite (CuSO₄·5H₂O), epsomite (MgSO₄·7H₂O)

Clean with compressed air, a soft brush, or gentle vacuum.

### Fragile Minerals

Soft or delicate minerals require special care:

- Selenite/gypsum (CaSO₄·2H₂O, Mohs 2) — scratches easily; clean with damp cloth
- Native sulfur (S, Mohs 1.5–2.5) — heat-sensitive; never use warm water
- Realgar (As₄S₄, Mohs 1.5–2) — light-sensitive and toxic; handle with gloves

## Ultrasonic Cleaners

Ultrasonic cleaners work well for hard, compact minerals (Mohs 6+) but can shatter fragile crystals, destroy fibrous minerals, and loosen matrix attachments. Use with caution.