Switch to preferred accessibility theme:

• High contrast
• Low graphics
• Mobile version
• Default theme

Increase or decrease the text size:

• Internet Explorer: View > Text Size > Largest

Keyboard navigation and access keys:

• A - Accessibility options
• 0 - Skip navigation
• 1 - Home
• 2 - Alexandrite chapters
• 3 - Alexandrite directory
• 4 - Alexandrite forums
• 5 - Alexandrite gemstones
• 6 - Alexandrite localities
• 7 - Contact information
• 8 - About Alexandrite Guide
• 9 - Sitemap
• Press ALT + Access Key, then ENTER.

This section has no relevant content published at this time.

AMA style

David Weinberg. "Definition of Ultramafic". In Alexandrite Tsarstone Collectors Guide. July 03, 2010, 04:43 UTC. Available at: http://m.alexandrite.net/viewpage.html?id=GG-080-00001. Accessed May 21, 2026.

APA style

"Definition of Ultramafic". (2010, July 03). In Alexandrite Tsarstone Collectors Guide. Retrieved 17:52, May 21, 2026, from http://m.alexandrite.net/viewpage.html?id=GG-080-00001.

Bluebook style

"Definition of Ultramafic", http://m.alexandrite.net/viewpage.html?id=GG-080-00001 (last visited May 21, 2026).

Bluebook: Harvard JOLT style

See Alexandrite Tsarstone Collectors Guide, "Definition of Ultramafic", http://m.alexandrite.net/viewpage.html?id=GG-080-00001 (A type of igneous rock characterized by a high content of mafic minerals, particularly olivine, pyroxenes, amphiboles, etc. The silica content is less than 45%.) (as of May. 21, 2026, 17:52 GMT).

CBE/CSE style

David Weinberg. "Definition of Ultramafic". In Alexandrite Tsarstone Collectors Guide. 2010 Jul 03, 04:43 UTC.[Internet], Alexandrite Tsarstone Collectors Guide; 2010 Jul 03, 04:43 UTC [cited 2026 May 21]. Available from: http://m.alexandrite.net/viewpage.html?id=GG-080-00001.

Chicago style

David Weinberg, "Definition of Ultramafic", http://m.alexandrite.net/viewpage.html?id=GG-080-00001, (accessed May 21, 2026).

MLA style

"Definition of Ultramafic". Alexandrite Tsarstone Collectors Guide. 03 Jul 2010, 04:43 UTC. 21 May 2026 http://m.alexandrite.net/viewpage.html?id=GG-080-00001

MHRA style

David Weinberg, "Definition of Ultramafic", Alexandrite Tsarstone Collectors Guide, 03 July 2010, 04:43 UTC, http://m.alexandrite.net/viewpage.html?id=GG-080-00001 [accessed 21 May 2026].