Corundum

specimen number:
1052690

location:
Cascade Canyon, San Bernardino Co., California, USA

description:

Purplish red crystal of corundum, this is the variety known as Ruby, measuring to 0.6 cm in size embedded up on matrix. The specimen comes with an antique label as shown at the end of the video. On this label this piece is described as coming from a new find in 1909.

The Cascade Canyon ruby locality referenced under San Bernardino County, California, represents a historic and highly specific geographic overlap with the classic San Gabriel Mountains corundum deposits, located right near the complex, modern-day county border lines of Los Angeles and San Bernardino counties. Geologically, this high-grade metamorphic deposit occurs within blocks of Precambrian-age dolomitic marble and pelitic schist belonging to the San Gabriel metamorphic complex, where intense granulite-facies regional metamorphism and chromium-bearing hydrothermal metasomatism allowed pink to deep red corundum crystals to precipitate. The resulting rubies develop as distinct hexagonal prisms and granular crystal aggregates embedded in a striking, highly contrasting matrix of snowy white marble, pale grey plagioclase, and bright green chromium-muscovite (fuchsite), displaying a brilliant carmine-red fluorescence under ultraviolet light. Historically, artisanal surface quarrying and small-scale trenching for gemstone and lapidary material were carried out intermittently by early twentieth-century prospectors and regional mineral clubs, with the most active periods of specimen extraction spanning from the late 1920s through the 1960s. Due to the exceptionally rugged, steep terrain and subsequent federal wilderness conservation enactments, large-scale commercial underground mining was never viable, and all organized extraction ceased by the late twentieth century.

Dr. Ludwig Eger (active c. 1870-1915) was a highly respected Austrian mineral dealer based in Vienna who played a significant role in the distribution of Central European and Alpine mineral specimens during the late 19th and early 20th centuries. Operating under the firm name "Dr. L. Eger," his business was situated in the heart of Vienna, a primary hub for scientific exchange during the Austro-Hungarian Empire. Eger was noted for his professional, academic approach to the mineral trade, often supplying high-quality, systematic collections to universities and major museums throughout Europe and North America. His labels are easily recognized by their classic 19th-century typography, typically featuring "Dr. L. Eger, Wien" (the German name for Vienna) and providing detailed locality and species data in a formal, structured format. In addition to minerals, Eger dealt in paleontological and zoological specimens, as was common for the natural history establishments of the time.

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