Shell
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Description
The hard outer covering or case of an animal, mollusk, insect, nut, or egg.
For more information see Eggshell, Seashell, Oyster shell, Tortoiseshell, and Walnut shell.
Synonyms and Related Terms
shells; seashell; tortoiseshell; eggshell; coquille (Fr.)
Risks
- No significant hazards.
- ThermoFisher: SDS
Physical and Chemical Properties
- Orthorhombic crystal system with platy or fibrous, acicular crystals that are often twinned
- Reacts with acids to evolve carbon dioxide.
- Aragonite is harder and denser than calcite.
- Fracture = subconchoidal.
- Luster = vitreous to resinous.
- Transparent to translucent.
- Streak = white
- Fluorescence = variable
- Birefringence = strong showing interference colors
- Straight extinction
| Mohs Hardness | 3.5 - 4.0 |
|---|---|
| Density | 2.93-2.95 g/ml |
| Refractive Index | 1.530, 1.682, 1.686 |
Resources and Citations
- Oppi Untracht, Jewelry Concepts and Technology, Doubleday & Co., Inc., New York City, 1985
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- A.Lucas, J.R.Harris, Ancient Egyptian Materials and Industries, Edward Arnold Publishers Ltd., London, 4th edition, 1962
- Art and Architecture Thesaurus Online, http ://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000