My current project is constructing a kiln from a local deposit of flint fire clay. The deposit is located on Hobart Butte in the town (to put it generously) of London, Oregon about ten miles south of Cottage Grove. I learned of the deposit while researching local materials at the university library in Ashland, Oregon. The geology section of most university libraries is a valuable resource in the search for local material, especially for stoneware. This particular deposit was thoroughly analyzed in the 1940's as a potential source of alumina and was mined for a time for the production of fire brick near Portland. The main ore body, which averages 30% alumina, is in excess of 90 million tons and the total deposit is over 200 million tons. Fortunately the aluminum industry hasn't figured out how to smelt anything other than bauxite and the deposit remains virtually untouched, The deposit, located on BLM land, composes, essentially, the entire top 1000 feet of the mountain and the old quarry face is accessible by a rather rough logging road. 4wd in the summer and forget it in the winter. The potential for this material to form the basis of a regional craftsman's economy is tremendous. It is the foundational material for the glass, metal and ceramic crafts and could be used for forge liners, smelting furnaces, glory holes, glass batch furnaces, lehrs and, of course, pottery kilns.
1 comment:
I love the post! It's great to see people who actually care about such things available to local crafts folk. I went to the Butte and took some samples, then had the samples tested by an assay company. Unfortunately, the Kaolin at Hobart Butte; the clay is VERY HIGH IN ARSENIC! The EPA has a max ppm of 10, and the material in the deposit tests at 18000ppm. For this reason, one shouldn't handle the material without protection and should definitely avoid firing it (due to toxic smoke) or using it in functional pottery (due to leeching of As, Pb, and Hg found in the kaolin.)
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