What are the differences between Aluminium Silicate and CRYSTALLINE
SILICA? Aren't they all kaolin? Why is CRYSTALLINE SILICA classified
as carcinogen, but Aluminium Silicate is not? Thanks.

Silica is Silicon Dioxide (Si02), not Aluminum Silicate. There are
various hydrated forms of Aluminum Silicate, one of which, called
Kaolinite, is a principle constituent of the Kaolin clays.

Crystalline Silica causes silicosis. It is carcinogenic probably for
similar reasons to Asbestos, by physically damaging cells. I don't
know anything about the toxicity of Aluminum Silicate or Kaolin, but
the MSDS (Material Safety Data Sheet) does not list it as a
carcinogen. Of course, that may just mean that it is not as highly
studied as Silica or Asbestos.

MSDS sheets are available online. See for example:

http://www.ilpi.com/msds/#Internet

Structurally, SiO2 silicates form crystalline structures that can
propagate in 3 dimensions forming small crystals.  You are most
familar with various sands that are used industrially, or on the beach
which are SiO2 silicates.  This class of compounds are classified as
carciogenic because the tiny silicate crystals will puncture cells
repeatedly which can cause changes in the cell which may become
cancerous.

Alumino-slicates form large (on a molecular scale) 2 dimensional
sheets which can be connected by various pillaring agents to form size
specific sieves.  Kaolin is an especially pure form of this structure
with few impurities from other metals such as iron, chromium, or zinc.
  These tiny clay tiles are on the order of a few microns in size but
are large enough and blunt enough not to adversely interact with
cells.

More specific information about crytalline silicate health effects can
be found at <a href="http://www.asosh.org/Programmes/SORDSA/Crystalline_silica.htm">http://www.asosh.org/Programmes/SORDSA/Crystalline_silica.htm</a>.