Earlier this month I made my first trip to the Carlsbad area of California, north of San Diego, to take GIA’s Colored Stones Grading and Pearl Grading labs. Before class started, however, I had my first gem adventure: a field trip to the Stewart Lithia Mine in Pala, California. This mine has a long history, over 100 years on and off, first mined for the lovely purple mineral lepidolite (for its lithium, used primarily in grease), and later for a variety of gems (most of them pink.) Pink, green, bi-color and black tourmaline is found here, as well as kunzite, morganite and heliodor (pink and yellow varieties of beryl), and quartz.
San Diego County is known for its pegmatite deposits — lenses of igneous rock with large/abundant crystals, usually a dozen feet thick, give or take — and the Stewart Lithia mine sits in an unbelievably thick pegmatite (120 feet thick, in some places.) The geology was quite interesting driving out to Pala from the coast, with mountains looking like piles of boulders, from a distance. (Okay, so it was interesting to me. Never mind.)
Gem-finding is hard work under the sun (which got uncomfortably warm, despite the low-for-San-Diego temperatures.) Fabulous gem rough was found, but not by me — a few chunks of gemmy rubellite (pink tourmaline) in the 30-40 carat range, and a gorgeous gemmy bi-color (green to seafoam blue) tourmaline crystal, easily two inches long. We were told to limit ourselves to ten pounds of rock apiece (!!), but I brought home a bit less since I had to fit it all in my suitcase.
After lunch, we toured the mine. I didn’t take many pictures inside (none with flash, out of respect for everyone’s low-light vision), but the workings were quite impressive.
In the lower levels, we saw a remarkable mineral formation, where white spodumene crystals against a dark grey background formed a perfect Chinese dragon, easily 15-18 feet long (complete with head, teeth, ear, eye and sinuous body.) At the bottom was a lake of pure, ancient water, rich in calcium. (If you breathe upon the water, the calcium absorbs the carbon dioxide you exhale and forms calcium carbonate crystals on the surface. Magical.) The water was quite drinkable, and tasted wonderfully smooth. I admit, the lake was my favorite part.
All in all, it was a wonderful day! If you’d like to see more pictures, check out the set on Flickr.