Difference between revisions of "Peridot"
| Line 10: | Line 10: | ||
== Physical and Chemical Properties == | == Physical and Chemical Properties == | ||
| − | * Orthorhombic crystal system | + | * Orthorhombic crystal system |
| − | * Fracture = conchoidal | + | * Fracture = conchoidal |
| − | * Luster = vitreous | + | * Luster = vitreous to oily |
| − | * Streak = colorless | + | * Streak = colorless |
* Fluorescence = none | * Fluorescence = none | ||
| + | * Pleochroism = weak yellow-green and green (noticeable only in dark stones) | ||
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||
! scope="row"| Composition | ! scope="row"| Composition | ||
| − | | (Mg,Fe) | + | | (Mg,Fe)<sub>2</sub>SiO<sub>4</sub> |
|- | |- | ||
! scope="row"| Mohs Hardness | ! scope="row"| Mohs Hardness | ||
| − | | 6.5 | + | | 6.5 - 7.0 |
|- | |- | ||
! scope="row"| Density | ! scope="row"| Density | ||
| Line 28: | Line 29: | ||
|- | |- | ||
! scope="row"| Refractive Index | ! scope="row"| Refractive Index | ||
| − | | 1. | + | | 1.64 - 1.70 |
| + | |- | ||
| + | ! scope="row"| Birefringence | ||
| + | | 0.035 - 0.038 (usually 0.036, moderate doubling) | ||
|} | |} | ||
Revision as of 09:31, 21 December 2022
Description
A transparent, yellow-green Gemstone. Peridot is a transparent form of Olivine that was known in ancient Greece and in Egypt. Many of the green stones worn by Cleopatra were peridot. The main old world source for peridot was the island of Zabargad (St. John's Island) in the Red Sea. Peridot was called an evening emerald because it appears to lose its yellowish cast at night. It has sometimes been misidentified as emerald and as green glass. Former names include topaz (Greek) and zerberdjet (Persian). Peridots are still obtained from Zabargad and also from Brazil (Minas Gerais), South Africa, Kenya, China, Myanmar (formerly Burma, near Mogok), Norway (Sondmore), and the U.S. (Arizona, Hawaii).
Synonyms and Related Terms
olivine; forsterite; zeberdjet; evening emerald; olivine, péridot (Fr.); peridoto (Esp., Port.); Peridot (Deut.); peridoot (Ned.)
Physical and Chemical Properties
- Orthorhombic crystal system
- Fracture = conchoidal
- Luster = vitreous to oily
- Streak = colorless
- Fluorescence = none
- Pleochroism = weak yellow-green and green (noticeable only in dark stones)
| Composition | (Mg,Fe)2SiO4 |
|---|---|
| Mohs Hardness | 6.5 - 7.0 |
| Density | 3.22-3.40 g/ml |
| Refractive Index | 1.64 - 1.70 |
| Birefringence | 0.035 - 0.038 (usually 0.036, moderate doubling) |
Comparisons
Properties of Common Gemstones
Resources and Citations
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 561
- Wikipedia: Peridot (Accessed Dec 2022)
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
- Website: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/Peridot/peridot_triple_page.htm
- Yasukazu Suwa, Gemstones: Quality and Value, Volume 1, Sekai Bunka Publishing Inc., Tokyo, 1999
- Michael O'Donoghue and Louise Joyner, Identification of Gemstones, Butterworth-Heinemann, Oxford, 2003