Ivor and Olive Lewis on tue 21 mar 06
Dear B J Clark,
As you may have gathered from recent discussions, this clay body has a =
proportion of Halloysite Clay in its composition. I am uncertain about =
the nature of Halloysite from New Zealand but information shows this =
member of the clay family does not have the same crystal shape as =
Kaolinite derived clays. There are two possibilities. One is an =
agglomeration of fibrous crystals into structures that look like =
snowballs, another is of fibrous tubes which can unroll as water affects =
them and roll up again as they dry out. It is not impossible that this =
may be the source of your troubles and the effects of excessive =
shrinking on the larger structures you are making.
In this region of South Australia we have a lot of problems with moving =
house foundations. This is because the soil is called Bay of Biscay. It =
has a excessive drying shrinkage and a sheet of mud will crack like a =
crazy paved patio. We suspect this is because the clay is a Halloysite =
type. the clay we get from beneath the soil is useless for making =
pottery.
I would be interested in reading other opinions.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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