Clay
What is Clay?
Clay is a naturally occurring earthy material composed primarily of fine-grained minerals, which typically contain hydrated silicates. It is formed through the weathering of rocks over long periods. Clay minerals are characterized by their plasticity when mixed with water, allowing them to be molded and shaped. The composition of clay varies depending on the source rock and the weathering processes involved, leading to a wide range of colors and properties. Clays are used extensively in various industries, including ceramics, construction, and as a component in many industrial processes.
Optical Properties
- Refractive Index
- Variable
- Birefringence
- Variable
- Pleochroism
- None
- Optical Character
- Biaxial
- Dispersion
- None
Discover Values
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Clay before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Clay Localities Map
See where Clay is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- Various, including white, gray, red, brown, yellow, and black
- Hardness (Mohs)
- 1-2.5
- Density
- 1.6-2.6 g/cm³
- Luster
- Earthy to dull
- Crystal System
- Amorphous
Chemical Properties
- Chemical Formula
- Variable, typically hydrated aluminum silicates
- Elements
- Si, O, Al, H, and other elements depending on the specific clay mineral
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Clay FAQs
How do I identify Clay?
Clay can be identified by its hardness of 1-2.5 on the Mohs scale, Various color, Earthy to dull luster, Amorphous crystal system. Look for these key characteristics when examining specimens.
What color is Clay?
Clay typically appears in Various, including white, gray, red, brown, yellow, and black. Color can vary depending on impurities and formation conditions.
How hard is Clay?
Clay has a hardness of 1-2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.