Real-Life Communication
One of your clients, a ceramics company, is interested in importing
a certain clay substance called kaolin. If you want their business, you'd
better rush to the books and find out about the stuff.
"We do a tremendous
amount of research, and have to slog through a lot of technical material,"
says trade specialist Walter Stunder, who's currently researching kaolin.
"The first thing was to find out exactly what this substance is. After reading
and researching extensively, we then wean out the important information and
compile it into a report."
You have been assigned to help Stunder.
As you begin your research, you have trouble finding out anything about kaolin
until you discover that in many parts of the world, kaolin is called china
clay. After you have this important piece of information, you dig out a document
about china clay.
Read the following material about china clay. By
answering the questions listed, you'll have gleaned the necessary information
that will eventually go into a report.
China Clay
China
clays are the purest clays. Most of them consist of kaolinite and don't contain
any other clay material. French deposits of china clay are believed to have
been formed by surface weathering -- downward percolating water containing
carbon dioxide.
China clays are primary or residual clays. They're
still at the site of their formation. This is one of their characteristics,
although the white-burning clays of South Carolina, Georgia and Florida are
referred to as sedimentary kaolins. Sedimentary usually implies secondary
deposits which have been washed away from the site of their formation. Most
clays other than china clay are sedimentary.
China clay is almost free
from discoloring oxides, so it fires to a white color. This property distinguishes
it from other clays, and makes the manufacturing of porcelain and china made
from china clay possible.
From a geological point of view, china clays
are very young clays and kaolinization is still taking place. The yield of
china clay is relatively small. For example, in Cornwall the china clay only
accounts for about 10 to 20 percent of the parent rock. For this reason, the
raw clay has to be refined so the china clay can be properly separated from
other materials.
Now that you've read through the report,
try to answer the following questions.
Questions
- What's surface weathering?
- How is residual clay different than sedimentary clay?
- Where are sedimentary china clays found?
- Why is china clay so valuable to porcelain manufacturers?