Feature
Gems & Gemology, Winter 2001, Volume 37, No. 4

Spessartine Garnet from Ramona, San Diego County, California

Peer Reviewed Article
Brendan M. Laurs, Kimberly Knox
For most of the 20th century, the principal source of fine spessartine was the area around the Little Three mine near the town of Ramona in southern California. Two pegmatites—the Hercules-Spessartite and the Spaulding dikes—yielded most of the estimated 40,000–50,000 carats of facet-grade rough mined from 1956 to 1994. Prized for its bright orangy yellow to yellowish orange color, Ramona spessartine has similar R.I. and S.G. values to those of most other pegmatitic gem spessartines. Typical internal features are wavy two-phase partially healed fractures, negative crystals, needles/tubes, growth patterns, and anomalous birefringence; mineral inclusions are rare. The composition of four samples (ranging from light orangy yellow to yellow-orange) was Sps94.8–88.8Alm4.7–11.0Gro0.5–0.2, and the absorption spectra of all samples showed strong peaks for Mn2+ and subordinate Fe2+ bands.

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