Mendocino Mineral Madness
by Katy Tahja, November 1, 2017
While researching Mendocino County’s geology as I prepare to write a 150-year history of Mendocino County I was re-reading “Mineral Commodities Of California” published in 1957. It’s a 736-page treasure with charts, maps and photos and I paid a whopping $1.00 for it at a yard sale. Hey, you get research books wherever you can find something relevant.
Did you know some of our rocks have asbestos within serpentine? Or that asphalt bituminous rock was found in Pt. Arena and graphite (pencil lead) was found in a claim 15 miles east of town? Chromite was found near Leggett and coal beds 14 feet thick were near Dos Rios near the Middle Fork of the Eel River? Manganese was mined from chert in the Franciscan rock formation on the eastern boundary of the county and there were nickel prospects in the north county and rhodochrosite deposits near Covelo.
The really fun discovery was about jade mining, with a photo, at Leech Lake northeast of Covelo. It’s a private in-holding within The Yolla Bolly-Middle Eel Wilderness. Checking with Big Sam Gitchell, who owns the Rock Stop at Floodgate on Highway 128, I found out this is one of the jade claims he now owns, along with the River Blossom jade claim in Trinity County. Sam and his family produce beautiful jewelry for the shop with locally sourced Botryoidal Jade.
If you want to find jade of your own on public land there are several books that can lead you to rockhounding sites in the county. "Gem Trails of Northern California,” “Rocks & Minerals of California,” and “Rockhounding California” are all good resources. One delightful old book I own is called “California Gem Trails” published in 1974 by Darold Henry. Little hand drawn maps decorate the book and the first chapter is Mendocino Gems. It talks about nephrite and jadeite and jaspers and tells you where to stop and look.
Rockhounding is great family adventure and dirt cheap, if you’ll excuse the pun. All it takes is gas money and a map. You don’t have to be a geologist to enjoy spotting pretty rocks and they’re great for decorating your garden paths. On public lands rocks are free for the taking. Every time I drive north on Highway 101 I stop along the Avenue of the Giants at Dyerville Flat. There used to be a town here, and a CCC camp during the Depression, all carried away by floodwaters. Right north past interpretative signage for the two forks of the Eel River joining is a road down onto the river bar. The road is easy to access in any car and when you walk the riverbank you find a myriad variety of interesting rocks thrown together by the two river forks.
Someday I want to find some crocidolite, just because I love the name. It’s a fibrous blue formation of asbestos, also called reibeckite and I’ve got it marked on a map for a future rockhounding trip.