Page 7 - Curriculum Visions Dynamic Book

 Aluminium sulphate (commonly known
as alum).
clay: a microscopically small plate-like mineral that makes up the bulk of many soils. It has a sticky feel when wet.
crystal: a substance that has grown freely so
that it can develop external faces. Compare with crystalline, where the atoms are not free to form individual crystals and amorphous where the atoms are arranged irregularly.
granite: an igneous rock with a high proportion of silica (usually over 65%). It has well-developed large crystals. The largest pink, grey or white crystals are feldspar.
igneous rock: a rock that has solidified from molten rock, either volcanic lava on the Earth’s surface or magma deep underground. In either case the rock develops a network of interlocking crystals.
Kaolinite
Kaolinite is a clay mineral found in many of the world’s soils. It is composed of sheets containing aluminium silicates. Kaolinite is a soft mineral whose crystals are too small to be seen even with an ordinary microscope.
Water molecules can be absorbed between the silicate sheets, which explains why soils shrink and swell with wetting and drying. Kaolinite is mined as china clay and used for porcelain, pottery, the filler in medicinal tablets, and also to make smooth-textured paper.
 The structure of many sheet minerals containing aluminium. Mica and kaolinite are good examples.
Also...
The chemical formula for
corundum is Al2O3 (aluminium oxide). There are three main types
of feldspar, varying only in the metal that bonds the sheets together. The chemical formula for these feldspars is KAlSi3O8 (potassium feldspar), CaAlSi3O8 (calcium feldspar) and NaAlSi3O8 (sodium feldspar). The chemical formula for muscovite
mica is KAl2(Si3Al)O10(OH)2 (potassium aluminosilicate)
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