Difference between revisions of "Jasper"
| Line 33: | Line 33: | ||
|- | |- | ||
! scope="row"| Birefringence | ! scope="row"| Birefringence | ||
| − | | undetectable to 0. | + | | undetectable to 0.004 |
|} | |} | ||
| + | |||
== Comparisons == | == Comparisons == | ||
Revision as of 11:05, 19 December 2022
Description
An opaque, dense cryptocrystalline Quartz stone. Jasper is associated with iron ores and contains irons impurities which give it a yellow, red, brown and occasionally green or blue color. The colors may be uniform, blotchy, or arranged in bands. When the colors are arrange in bands, the mineral is called riband jasper. A variety containing red and green alternating bands is called Siberian jasper. Jasper has been gathered or mined since Paleolithic times. Red, yellow and green jasper was used by the Egyptians for carved cylinder seals and amulets. Egyptian jasper is a variety that is red with brown areas. It was primarily used in the Middle Kingdom period. Currently, jasper is cut and polished as a ornamental building stone. Black jasper and black slate have long been used as touchstones to determine the presence of gold in gold-silver alloys.
Synonyms and Related Terms
riband jasper; Siberian jasper; chalcedony; Jaspis (Deut.); jaspe (Esp., Fr., Port.); isapidem (Lat.); iaspis (Gr.); yashp (Persian); jaspis (Ned.)
Physical and Chemical Properties
- No visible crystals
- Fracture = conchoidal, uneven, splintery
- Luster = waxy to vitreous
- Streak = white
- Fluorescence = generally inert
- Pleochroism = absent
| Composition | SiO2 |
|---|---|
| Mohs Hardness | 6.5-7.0 |
| Density | 2.59-2.61 g/ml |
| Refractive index | 1.535 - 1.539 |
| Birefringence | undetectable to 0.004 |
Comparisons
Properties of Common Gemstones
Additional Images
Red jasper pebble
Jasper
Jasper
Resources and Citations
- Mineralogy Database: Quartz
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
- 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
- Encyclopedia Britannica, http://www.britannica.com Comment: "jasper" [Accessed November 6, 2001].
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia: Jasper (Accessed Sept. 7, 2005 and Dec 2022)
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998