A geology index — 0 compatible sensors — Last revised June 1, 2025
Clay
Clay Index
Geological index for detecting clay minerals in rocks and soils. Particularly effective for identifying clay-rich areas and alteration zones associated with hydrothermal processes.
Used in mineral exploration.
When to use
- Mineral exploration target identification in arid and bare-ground regions
- Hydrothermal alteration zone mapping
- Lithological unit discrimination
- Iron oxide and clay mineral mapping
- Pre-field reconnaissance for geological surveys
- Clay Mineral Detection
- Geological Mapping
Limitations
- Vegetation cover masks underlying mineral signatures — works best on bare ground
- Atmospheric water vapour absorbs in similar SWIR regions, requiring correction
- Particle size and mineral mixtures produce non-linear spectral mixing
- Should be combined with field validation — single-index identification is unreliable
- Different mineral assemblages can produce similar spectral signatures
- Requires sensors with SWIR bands — not available on all platforms
General Formula
Sensor-Specific Formulas
Most-used sensors — click to show code below
| Sensor | Provider | Formula | Band Mapping |
|---|
Code Examples
clay_generic.py
Clay vs other geology indices
| Index | Name | How it differs |
|---|---|---|
| AKP | Alunite/Kaolinite/Pyrophylite Index | Alternative geology index — different band combination |
| ALT | Alteration Index | Alternative geology index — different band combination |
| AMP | Amphibole Index | Alternative geology index — different band combination |
| DOL | Dolomite Index | Alternative geology index — different band combination |
Related Geology Indices
References
Kalinowski & Oliver (2004)
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