Caliche
Caliche is a hardened calcium carbonate-rich soil or sediment layer, also called calcrete or hardpan, common in arid and semi-arid regions.
_1.jpg?width=760)
Caliche properties at a glance
| Type | Sedimentary Rocks |
|---|---|
| Chemical formula | Calcium carbonate-cemented sediment |
| Mohs hardness | 3 |
| Luster | dull |
| Streak | White to pale tan |
| Cleavage | Variable by mineral grains |
| Fracture | Earthy to uneven |
| Specific gravity | 2.4 |
| Transparency | opaque |
| Common colors | White, Cream, Tan, Gray, Brown |
| Rarity | common |
Geology & background
Forms in soils and near-surface sediments where calcium carbonate precipitates and cements grains into hard layers or nodules.
Caliche is useful in interpreting ancient soils, dry climates, and near-surface carbonate cementation.
How to identify Caliche
- Look for hard, pale, earthy carbonate cement in soil-like or near-surface material.
- Caliche is common in dry-region soils and may occur as nodules, crusts, or ledges.
- It may fizz with dilute acid because it contains calcium carbonate.
- Texture can include cemented sand, gravel, clay, or root-like structures.
Where Caliche is found
Caliche occurs in many sedimentary settings worldwide; exact locality should be verified from field notes, maps, or specimen provenance.
How much is Caliche worth?
| Entry-level specimen | $1 |
|---|---|
| Typical collector specimen | $10 |
| Premium specimen | $75+ |
Caliche is usually valued for teaching, field context, locality, texture, fossils, color, or unusual structures rather than high gem value.
Common uses
- Field identification
- Education
- Paleosol study
- Local construction material in some regions
Interesting facts
- Caliche is often a soil-related carbonate deposit rather than a typical bedded marine rock.
- It can cement sand, gravel, silt, or clay into hard crusts and nodules.
- Caliche layers can record dry climate and landscape stability.
Care & safety
Caliche can be soft, porous, crumbly, or weakly cemented depending on grain size, cement, and weathering.
Avoid inhaling dust. Do not cut, grind, or polish unknown sedimentary rocks without eye protection and a properly rated respirator.
.jpg?width=320)
_1_(26052651216).jpg?width=320)
