Sillimanite Value, Price, and Jewelry Information


The fibrolite from Burma and Sri Lanka is well known to gem collectors, and highly prized because of its great scarcity. Blue and greenish gems are lovely, although very difficult to cut. Chatoyant material sometimes yields catseye fibrolites, which are also very rare. The material from Kenya is just as attractive as Burmese fibrolite but seems to be somewhat smaller in size.

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The fibrolite from Burma and Sri Lanka is well known to gem collectors, and highly prized because of its great scarcity. Blue and greenish gems are lovely, although very difficult to cut. Chatoyant material sometimes yields catseye fibrolites, which are also very rare. The material from Kenya is just as attractive as Burmese fibrolite but seems to be somewhat smaller in size.

SILLIMANITE: Fibrolite, Kenya (0.34), Burma (2.44). Photo © Joel E. Arem, PhD, FGA. Used with permission.

SILLIMANITE (=FIBROLITE) Trimorphous with Kyanite, Andalusite.

Optics: a =1.654-1.661 β= 1.658-1.662; γ= 1.673-1.683.

Biaxial (+), 2V: 21—30°.

Occurrence: A mineral of metamorphic rocks, such as schists and gneiss; also granites.

Idaho; South Dakota; Oklahoma; Pennsylvania; New York; Connecticut; Delaware;  North Carolina; South Carolina.

Canada; Ireland; Scotland; France: Germany; Czech Republic; Slovakia; Brazil; India; Madagascar; North Korea; South Africa; Tanzania.

Sri Lanka and Burma: green, blue. violet—blue facetable material; also from Sri Lanka, grayish green, chatoyant fibrolite.

Kenya: facetable crystals, pale bluish color to colorless, S.G. 3.27.

Comments: The fibrolite from Burma and Sri Lanka is well known to gem collectors, and highly prized because of its great scarcity. Blue and greenish gems are lovely, although very difficult to cut. Chatoyant material sometimes yields catseye fibrolites, which are also very rare. The material from Kenya is just as attractive as Burmese fibrolite but seems to be somewhat smaller in size.

Name: After Benjamin Silliman, mineralogist, of Yale University. Fibrolite is in allusion to the fibrous nature of this variety.


Joel E. Arem, Ph.D., FGA

Dr. Joel E. Arem has more than 60 years of experience in the world of gems and minerals. After obtaining his Ph.D. in Mineralogy from Harvard University, he has published numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world.

Co-founder and President of numerous organizations, Dr. Arem has enjoyed a lifelong career in mineralogy and gemology. He has been a Smithsonian scientist and Curator, a consultant to many well-known companies and institutions, and a prolific author and speaker. Although his main activities have been as a gem cutter and dealer, his focus has always been education. joelarem.com

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