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B Clay

Alternate Names: 3B, PR#3 B

Description: Buff firing highly vitreous, medium plasticity, stoneware clay

Oxide Analysis Formula
Na2O 0.10% 0.01
Al2O3 17.70% 1.00
MgO 0.60% 0.09
SiO2 67.80% 6.50
K2O 2.70% 0.17
CaO 0.24% 0.02
P2O5 0.02% -
TiO2 0.70% 0.05
Fe2O3 1.30% 0.05
MnO 0.01% -
LOI 6.50%n/a
SO3 0.10%n/a
Oxide Weight 525.39
Formula Weight 562.51


High temperature clean buff firing stoneware clay mined at Ravenscrag, Sask. Analysis updated July 97.

There is some argument about whether the mineralogy should be muscovite or illite. Here is the comment of one technician: "With regards to illite or muscovite, the only way to categorically differentiate between the two is to determine the layer charge (most easily by electron microscopy) which I didn't do. In this sample, the mica component has no detectable expandability which suggests a high-charge mica with very little depotassification typical of muscovites. Also, the x-ray scattering domain size is quite large with minimal disorder which you seldom find in illite but expected for muscovite. However, the kaolinite in the sample is extremely fine as one would see in fireclays. 41% quartz in the sample is accurate. You can easily verify this from your chemistry by checking the contributions of muscovite, kaolinite, smectite and K-spar to the total SiO2, and constraining potassium to
muscovite and K-spar, and Mg to smectite. From my experience, a high plasticity and the apparent illitic properties that you see in the clay is most likely due to the discrete smectite content (8%). Note that the activity of smectite is several orders of magnitude (up to 10 times) greater than the finest kaolinite or illite."

Major trace elements:
424 Ba ppm
34 Sr pmm
24 Y ppm
10 Sc ppm
249 Zr ppm
1 Be ppm
65 V ppm

Related Information

Ravenscrag Saskatchewan clays fired at cone 10R

Glazeless (top) and with glaze (bottom): A1 (bentonitic), A2 (ball clay), A3 (stoneware), 3B (porcelains), 3C (lignitic ball clay), 3D (silt). The bottom row has also shows soluble salts (SOLU test).

Mel Noble at Plainsman Clay's Ravenscrag, Saskatchewan quarry

Whitemud formation layers

Plainsman Clays extracts 6 different sedimentary clays from this quarry (Mel knows where the layers separate). The dried test bars on the right show them (top to bottom). The range of properties exhibited is astounding. The top-most layer is the most plastic and has the most iron concretion particles (used in our most speckled reduction bodies). The bottom one is the least plastic and most silty (the base for Ravenscrag Slip). The middle two are complete buff stonewares made by mother nature (e.g. M340 and H550). A2, the second one down, is a ball clay (similar to commercial products like OM#4, Bell). A2 is refractory and the base for Plainsman Fireclay. The second from the bottom fires the whitest and is the most refractory (it is the base for H441G).

Mother Nature's Porcelain - From a Cretaceous Dust Storm!

Plainsman Clays did 6 weeks of mining in June-July 2018 in Ravenscrag, Saskatchewan. We extracted marine sediment layers of the late Cretaceous period. The center portion of the B layer is so fine that it must have wind-transported (impossibly smooth, like a body that is pure terra sigillata)! The feldspar and silica are built-in, producing the glassiest surface I have ever seen at cone 6 (2200F). Despite this, pieces are not warping in the firings! I have not glazed the outside of this mug for demo purposes. I got away with it this time because the Ravenscrag clear glaze is very compatible (similar thermal expansion). But with other less compatible glazes they cracked when I poured in hot coffee. This mug was the beginning of an exciting project the sieve out +325 mesh particles any make many more pieces.


Minerals Quartz
Quartz is the most abundant mineral on earth, it is the main crystalline mineral form of silica (SiO
Minerals Kaolinite
The most fundamental clay mineral. This mineral is found in nature in its purest form as kaolin. How
Minerals Smectite
A highly plastic clay mineral related to montmorillonite (bentonite), more correctly, the name of th
Minerals Muscovite
A form of mica often found as micro-flakes in processed raw clays. It can often be found in the mine
Minerals Illite
A clay. A sedimentary weathered alteration of muscovite mica. Some stoneware clays contain illite. I
B Clay Data Sheet
Materials A3 Stoneware Clay
Typecodes Clay Other
Clays that are not kaolins, ball clays or bentonites. For example, stoneware clays are mixtures of all of the above plus quartz, feldspar, mica and other minerals. There are also many clays that have high plasticity like bentonite but are much different mineralogically.
By Tony Hansen
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