sedimentary
Caliche / Conglomeratic Limestone
Calcareous duricrust / Caliche
AI-generated identification · may be incorrectHardness 3-4 (Mohs), grayish-white to buff-tan color, dull earthy luster, amorphous to microcrystalline texture with embedded clasts, specific gravity 2.2-2.6.
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Physical properties
Hardness 3-4 (Mohs), grayish-white to buff-tan color, dull earthy luster, amorphous to microcrystalline texture with embedded clasts, specific gravity 2.2-2.6.
Formation & geological history
Forms in arid or semi-arid environments where dissolved calcium carbonate precipitates from evaporating groundwater, cementing soil, sand, and gravel over thousands of years.
Uses & applications
Commonly used in construction as aggregate, road sub-base material, and historically burned to produce quicklime.
Geological facts
Caliche layers can be so dense that they form impenetrable hardpans that prevent plant roots from penetrating deep underground.
Field identification & locations
Identified by its chalky-white to grey nodular crust and vigorous effervescence with dilute hydrochloric acid. Abundantly found in desert regions worldwide.
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