A geology index — 0 compatible sensors — Last revised June 1, 2025
AKP
Alunite/Kaolinite/Pyrophylite Index
Geological index designed to identify alunite, kaolinite, and pyrophylite minerals. These clay minerals are indicators of hydrothermal alteration and are valuable for mineral exploration and geological mapping.
Used in water detection, and 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
- Hydrothermal Alteration Mapping
- Clay Mineral Detection
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
akp_generic.py
AKP vs other geology indices
| Index | Name | How it differs |
|---|---|---|
| ALT | Alteration Index | Alternative geology index — different band combination |
| AMP | Amphibole Index | Alternative geology index — different band combination |
| Clay | Clay Index | Alternative geology index — different band combination |
| DOL | Dolomite Index | Alternative geology index — different band combination |
Related Geology Indices
References
Rowan & Mars (2003)
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