Page 6 - lw3518

4 THE PACIFIC MINERALOGIST

It is known that clay deposits were lish ball clays are mined from the
accessible to the Chaldeans and North and South Devon and Darts-
Assyrians,as they erected the pal- mouth areas.
aces of Croesus, Mausolus and Atta- The importation of English Kaolin,
lus in beautiful red fired brick. by this country, before the present
Tombs of that era were sometimes war, averaged over 500,000 _tons
made of a sing le . piece of pottery annually-part of which was used
ware, or of two sections fitted togeth- by the paper trade. Due to uncertain
er. The ancient cities of Nineveh and deliveries and unstable prices, this
Babylon were constructed of yellow- importation has been rapidly de-
ish white brick and coated with grey creasing.
ish and yellow glazes. The largest deposits of domestic
The early Greek potters mined Kaolin are the residual deposits of
deposits of very fine clays, which North Carolina, South Carolina, and
they probably washed and fired at Georgia; and the sedimentary de-
high temperatures. This is evidenced posits of Florida and Georgia . These
by the special hardness and fine- clays compare favorably · with the
ness of the clay wares of that period. English Kaolins, although these de-
The first use of clay in China dates posits are not as well developed
to 2700 B.C. when the first pieces of nor are they as large and uniform
pottery were made by Kouen-Ou, as the English.
during the reign of Emperor Hoang- Domestic ball clays are mined
Ti. It was not until 200 B.C. that the chiefly in Tennessee and Kentucky.
large deposits of Kaolin, in China, These clays have been used by East-
were used to develop a true hard ern manufacturers since 1890. Until
porcelain ware. recently however, the West Coast
Many centuries later in 1765, the potters have been able to buy the
famous Kaolin beds of St. Y rieix, English clay cheaper, due to the diff-
France, were discovered. Three erence in rail and water transport-
years later in 1768, the vast Cornish ation costs.
oeds of Kaolin, in England, were In Southern California, we have
found. These discoveries of kaolin, a number of clays of local import-
the essential clay in the manufacture ance. The Alberhill clays in the Lake
of hard porcelain, assured the supre- Elsinore district have been used ex-
macy of hard porcelain ware on the tensively in the manufacture of fire
continent of Europe. brick, terra-cotta, drain tile, sewer
Natives of the American Conti- pipe, storeware and roofing tile.
nent were producing exceptionally California has two Kaolin deposits
fine terra-cottas, in Mexico and Cent- being mined and marketed. One of
ral America, as early as 1000 B.C. these clays, located in Orange Coun-
Thus, the manufacture and use cf ty, is approximately 40 percent clay
clay wares was discovered by three and 60 percent silica, as mined. By
different peoples, the Egyptians, a process of crushing and washing
Chinese and Mexicans (aztecs) at the silica is seperated from the clay,
the beginning of their· respective producing a Kaolin, very close to the ..._
civilizations, and at a date too re- English type. The silica is recovered.
mote to be accurately determined. and ground for the pottery and foun-
Deposits. Some of the best known dry trade.
clay deposits are the English Kaolin The second Kaolin deposit is
beds in and near the St. Austell dis- located in Mono County, and was
trict, which produce a fine white formed by the alteration of rhyolite
burning clay of residual origin. Eng- ( continued on page 25)