Can someone test my clay?

I would be hard pressed to attempt to fire the clay knowing nothing about it. I would hate to have it melt all over the kiln. If you bought some commercial clay, then you would know what cone to fire it. Good luck. Steve in Tampa, Florida

trick is to make a few thumb pots of known s/ware clay, and then put a sample of your clay in each... fire 1 to bisque 1000c (ish) 1 to e/ware

Eddie:

I'm assuming that the OP's native clay is the usual earthenware "secondary" type, found in streambeds and all too many back yards. This would melt completely at 1200C (cone 6). (Mine does, and makes a nice "Albany slip" glaze over a stoneware clay.)

But it would be interesting to know how commonly one can expect to find stoneware clays in the wild. I think these need to be "primary" clays, weathered out of a granite cliff right into a local deposit. So I suspect there need to be mountains around... something we don't have where I live (Ann Arbor, Michigan), but obviously not everyone is so handicapped. ;-)

Does anyone know of stoneware clays found in non-mountain locations? How does one go about finding these?

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

I'm about 1.2 hours Southeast of you in the heart of the Northwest Ohio Black Swamp. Ancient lakebed, flat as you can get. I am on a rocky ridge though. I dug about

I only have to dig a couple of feet or less to hit clay in my garden, but since this is a subdivision, that depth is undoubtedly in the region that has been disturbed by the developer's original contouring.

Michigan has been extensively modified by glaciers, so I have no idea if there are any primary deposits around... but I seriously doubt it.

Your rocky ridge might be a source of granite from which primary clay could erode. The question is where it would go after erosion. Most of the time, it is swept along and tumbled by stream action, and ends up as secondary clay somewhere else. I suspect that you need some sort of "settling basin" right below the ridge in order to have the primary clay end up there.

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Oops, my mistake! It seems only kaolin and similar porcelain clays are primary types, and everything else is secondary, washed to its present location by water. In fact, my garden clay is not mature at cone 2, but melted by cone 6, so it's somewhere between low-fire earthenware and high-fire stoneware. I don't know how to tell other than by testing.

Sorry for the confusion...

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis