Nepheline
Description
A feldspathic rock composed of sodium aluminum or potassium aluminum silicate. Nepheline occurs worldwide with rich deposits in the Russia (Kola Peninsula), Italy (Vesuvius), Norway, Canada (Ontario), and South Africa. This transparent to translucent mineral is characterized by the absence of Quartz. It tends to have a greasy feel with colorless, pale yellow, green, or brown stones. Nepheline is used as a flux in the manufacture of Glass, ceramics, and enamels.
Synonyms and Related Terms
nephelite; nepheline syenite; eolite; Carnegieite (synthetic), nefelina (Esp., Port;); nefelien (Ned.)
Risks
Inhalation and ingestion may cause respiratory and gastrointestinal irritation.
Physical and Chemical Properties
Hexagonal system, crystals rare; usually occurs as small grains or large masses. Good cleavage in three directions.
Fracture = subconchoidal. Luster = greasy (massive) to vitreous (crystalline). Streak = white
Transparent crystals become cloudy when placed in a strong acid solution.
| Composition | (Na,K)(AlSi)2O4 |
|---|---|
| Mohs Hardness | 5.5 - 6.0 |
| Density | 2.55-2.65 |
| Refractive Index | 1.526 - 1.546 |
Resources and Citations
- Mineralogy Database: Nepheline
- Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
- Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992
- Encyclopedia Britannica, http://www.britannica.com Comment: "nepheline" [Accessed December 4, 2001]. (tech info) (B/W photo)
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia: http://en.wikipedia.org/wiki/Nepheline (Accessed Sept. 10, 2005)
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 600,
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976 Comment: p. 1606 ( a feldspathoid type mineral)
- 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