Shell
What is Shell?
Shells are the hard, protective outer layers created by marine animals, primarily mollusks. They are composed mainly of calcium carbonate, often with some organic components. Shells come in a vast array of shapes, sizes, colors, and textures, reflecting the diversity of the creatures that create them and the environments they inhabit. Their formation involves the secretion of calcium carbonate by the mantle, a tissue layer within the animal. The shell's structure can be simple or complex, with layers that provide strength and protection. Shells are found in oceans, seas, and freshwater environments worldwide, and have been used by humans for tools, decoration, and as a source of food for millennia.
Optical Properties
- Refractive Index
- Variable
- Birefringence
- Variable
- Pleochroism
- None
- Optical Character
- Variable
- Dispersion
- None
Discover Values
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Shell 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.
Shell Localities Map
See where Shell 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, brown, pink, yellow, and iridescent colors
- Hardness (Mohs)
- 2.5-3.5
- Density
- Variable
- Luster
- Pearly to dull
- Crystal System
- Amorphous
Chemical Properties
- Chemical Formula
- CaCO3 (primarily)
- Elements
- Ca, C, O
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Shell FAQs
How do I identify Shell?
Shell can be identified by its hardness of 2.5-3.5 on the Mohs scale, Various color, Pearly to dull luster, Amorphous crystal system. Look for these key characteristics when examining specimens.
What color is Shell?
Shell typically appears in Various, including white, brown, pink, yellow, and iridescent colors. Color can vary depending on impurities and formation conditions.
How hard is Shell?
Shell has a hardness of 2.5-3.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.