Minerals in Art: Pigments Through History

## 40,000 Years of Mineral Pigments

The first artists ground minerals into powder and mixed them with animal fat to create cave paintings. The same mineral pigments were used by Egyptian tomb painters, Renaissance masters, and Impressionists. Many remain in use today.

## The Pigment Palette

### Red Pigments

| Pigment Name | Mineral Source | Formula | Mohs | Era of Use |
|-------------|---------------|---------|------|------------|
| Red ochre | Hematite | Fe₂O₃ | 5–6.5 | 40,000+ years — oldest known pigment |
| Vermilion | Cinnabar | HgS | 2–2.5 | Ancient Rome through 19th century |
| Realgar | Realgar | As₄S₄ | 1.5–2 | Ancient Egypt, China (toxic) |
| Red lead (minium) | Minium | Pb₃O₄ | 2.5 | Roman era through Renaissance |

### Blue Pigments

| Pigment Name | Mineral Source | Formula | Mohs | Era of Use |
|-------------|---------------|---------|------|------------|
| Ultramarine | Lazurite (lapis lazuli) | Na₃Ca(Al₃Si₃O₁₂)S | 5–5.5 | Medieval through present (most expensive) |
| Azurite blue | Azurite | Cu₃(CO₃)₂(OH)₂ | 3.5–4 | Ancient Egypt through Renaissance |
| Egyptian blue | Cuprorivaite (synthetic) | CaCuSi₂O₆ | 5 | 2600 BCE — first synthetic pigment |

### Green Pigments

| Pigment Name | Mineral Source | Formula | Mohs | Era of Use |
|-------------|---------------|---------|------|------------|
| Malachite green | Malachite | Cu₂(CO₃)(OH)₂ | 3.5–4 | Ancient Egypt through 18th century |
| Green earth (terre verte) | Celadonite/glauconite | K(Mg,Fe)(Fe,Al)Si₄O₁₀(OH)₂ | 2 | Roman era through Renaissance |
| Verdigris | Copper acetate (from native Cu) | Cu(CH₃COO)₂ | — | Medieval through 18th century |

### Yellow Pigments

| Pigment Name | Mineral Source | Formula | Mohs | Era of Use |
|-------------|---------------|---------|------|------------|
| Yellow ochre | Goethite/limonite | FeO(OH) | 5–5.5 | 40,000+ years |
| Orpiment | Orpiment | As₂S₃ | 1.5–2 | Ancient (toxic, light-sensitive) |
| Naples yellow | Lead antimoniate | Pb₂Sb₂O₇ | — | Mesopotamia through 19th century |

### White Pigments

| Pigment Name | Mineral Source | Formula | Mohs |
|-------------|---------------|---------|------|
| Chalk white | Calcite (chalk) | CaCO₃ | 3 |
| Gypsum white | Gypsum | CaSO₄·2H₂O | 2 |
| Lead white | Cerussite | PbCO₃ | 3–3.5 |
| Titanium white | Rutile | TiO₂ | 6–6.5 |

## The Price of Ultramarine

Lapis lazuli ultramarine was the most expensive pigment in history, worth more than gold by weight. Extracted exclusively from mines in Badakhshan, Afghanistan, it required weeks of grinding and purification. Vermeer, Raphael, and Titian used it sparingly. Synthetic ultramarine was invented in 1826, making the color affordable for the first time.

## Toxic Heritage

Many historic pigments are dangerously toxic:

- **Cinnabar/vermilion**: Mercury compound
- **Orpiment/realgar**: Arsenic compounds
- **Lead white/red lead**: Lead compounds
- **Emerald green (Scheele's green)**: Copper arsenate — possibly killed Napoleon (arsenic-laced wallpaper)

Modern pigments have largely replaced these with safer synthetic alternatives, but mineral-based ochres, umbers, and siennas remain in use.