Mel Noble at Plainsman Clay's Ravenscrag, Saskatchewan quarry

Plainsman Clays extracts 6 different sedimentary clays from this quarry, it was opened in the 1970s. The test bars were made by slaking select lumps from each layer (thus exhibiting their best performance). The left-most dried test bars show the layers (top to bottom). The top-most A1 is the most plastic and has the most iron contamination (it is used in our most speckled reduction firing bodies). A2, the second one down, is a ball clay (similar to commercial products, although darker burning), it is very refractory and the base for Plainsman Fireclay. A3, third from top, is a complete buff high-temperature stoneware (like H550), although sandy and over-mature at cone 10. 3B, third from bottom, is a smooth medium-temperature stoneware; it contains significant natural feldspar (although fired color and particulate contamination are the most variable). The second from the bottom, 3C. fires the whitest and is the most refractory (it is the base for H441G). The bottom one, 3D, the best product in the quarry. Although the least plastic and most silty, it is also very fine particled and the cleanest (consistently free of particulate impurities and sand), it pairs very well with a ball clay to make a cone 6 stoneware.

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Plainsman Ravenscrag Quarry in 2025:

It is Getting Complicated

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This has served the company for almost 50 years. The grinding plant, which has also served 50 years, has been able to process these clays to 20 and 42 mesh. While this quarry has been a key advantage for the company and coarsely ground bodies still sell well, the demand for smoother, more plastic and whiter bodies has seen a steady trend to the use of more and more imported 200 mesh powders (eg. clays, feldspar, silica) to make bodies. The star clay in the quarry is 3B, it is smooth and contains natural feldspar. Minings are typically done now just to get it. But because it is near the bottom (there are 6 layers plus overburden), others continue to bloat the inventory of unneeded materials (some of these piles are 30+ years old). On the next mining, the cost of stockpiling the overlying layers vs discarding them will have to be rationalized.

Most of these piles (especially the ball clay) could be sold on the open market if 200 mesh grinding was possible. The most serious problem is the amount of overburden that must be removed. Perhaps even more serious, since other clays are not needed, the 3B has to bear the entire cost of the mining. Now that better, more accessible and easier to mine clays further east have been found, the way forward is looking much better. In fact, it looks so promising (with testing of course) that it could be time to begin reclaiming this site.

This quarry has one saving grace: The bottom layer, which has been left in the ground the last two minings, 3D. It is the clean (low in contaminants) and, like 3B, contains natural feldspar. But it is not plastic, its usefulness depends on a better quality ball clay.

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Links

URLs	https://plainsmanclays.com/index.php?menupath=18 About Plainsman Clays
URLs	https://plainsmanclays.com/ Plainsman Clays Website - This is authored by Digitalfire and is a reference website in its own right. It provides unparalleled documentation of clays and recipes and processes used by the potter customers.
Glossary	Secondary Clay Clays form by the weathering of rock deposits over long periods. Primary clays are found near the site of alteration. Secondary clays are transported by water and laid down in layers.
Glossary	Clay What is clay? How is it different than dirt? For ceramics, the answer lies on the microscopic level with the particle shape, size and how the surfaces interact with water.
Glossary	Plainsman Clays A clay mining and processing company in Southern Alberta since 1965.
Materials	A1 Ball Clay It is very high in iron stone (pyrite) concretions and soluble iron salts, a heavily stained bentonitic ball clay.
Materials	A2 Ball Clay A refractory ball clay with pyritic iron impurities.
Materials	A3 Stoneware Clay A buff burning, high temperature somewhat sandy stoneware having ready-to-use plasticity.
Materials	3C White Ball Clay Lignitic, white burning refractory ball clay
Materials	3B Clay A fine-grained, tan burning, illitic stoneware with particulate and soluble salt impurities
Materials	3D Clay Fine particled, clean, silty stoneware clay containing natural feldspar
Projects	Plainsman 3D, Mother Nature's Porcelain/Stoneware
Projects	Mother Nature's Porcelain - Plainsman 3B This Saskatchewan clay contains natural feldspar, quartz and a variety of clay minerals, all blended by nature, to produce a porcelain, that although not white-burning, rivals or exceeds the strength achievable using industrial imported minerals
Articles	How to Find and Test Your Own Native Clays Some of the key tests needed to really understand what a clay is and what it can be used for can be done with inexpensive equipment and simple procedures. These practical tests can give you a better picture than a data sheet full of numbers.

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