Kaolin, also called china clay,
is a soft white clay
(aluminosilicate) that is an essential ingredient in the
manufacture of china and porcelain and is widely used in the making
of paper, rubber, paint, refractories, plastics, sanitary wares,
fiberglass, adhesives and many other products.
Kaolin is named after the hill in
China (Kao-ling) from which it was mined for centuries. Samples of
kaolin were first sent to Europe by a French Jesuit missionary
around 1700.
This minning site, with an area of
200 hectares of sedimentary china clay, is located near Barqueiros
- Barcelos. This deposit is essentially
composed by Kaolinitic sand layers. Then in the western area of the
deposit there is a level of quartzitic pebbles that decreases in
thickness and finishes in the eastern area.
The kaolinitic levels go from
extremely high degrees of whiteness to a shade of yellow. The
extraction method is through excavation and is than transported
from the sites to the storage or the washing area. This is the most
suitable method to allow a good selection of the
material.
The china clay is extremely fine and
the silica sand of round grain. The sand from the whitest levels
have a extremely low percentage of iron.
The quartizic peblles are white, but
when wet show spots and grooves which makes a chameleon pebble.
These pebbles exist in several sizes.
This mine have millions of tons of
raw material reserves.
Your mission to claim this earthcache
is one of the following options:
Option a: Take a picture with your GPS and
kaolin in the background and post with your log and send me an
email with the kaolin (aluminosilicate) chemical formula.
Option b: Send me an email with the red text
found at N41º 28.957’ W008º 44.149’ and N41º
29.020’ W008º 44.182’ and the kaolin (aluminosilicate) chemical formula.
