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QUARTZ AND SAND. 
Quartz, probably the most generally known mineral, con 
sists of silica (Si0 2 ). It belongs to the hexagonal system of 
crystallization and has a hardness of 7 on Mohs’ scale. It is 
colourless or white when pure, though often found tinted by im 
purities, such as manganese and carbonaceous matter. The 
varieties amethyst, rose quartz, and smoky quartz derive their 
typical colours from such impurities. 
Quartz is an essential constituent of many rocks. In the 
case of quartzite and sandstone, these rocks may consist entirely 
of quartz. Quartz may exist in the form of veins, or as the 
filling of cavities, in all rocks. 
Flint is a somewhat impure crypto-crystalline variety of 
quartz, which occurs in chalk deposits. 
Sand is the granular material resulting from the weathering 
and disintegration of rocks. It usually consists principally of 
grains of quartz. This is largely due to the hardness of quartz 
and its chemical stability. This natural concentration is effected 
by the weathering out of the other minerals of the rock. When 
the sand contains only a few per cent of the minerals other than 
quartz it is called silica sand or quartz sand. 
TRADE NAMES OF SANDS. 
Most of the trade names of sands are descriptive of either 
their mode of occurrence or their uses. 
River sand is the name applied to sand, of any grade, which 
is taken from the shores or beds of rivers. It is, as a rule, fairly 
free from impurities of a clay-like nature, though it may contain 
large percentages of feldspar, mica, hornblende, magnetite, etc. 
Lake sand is that taken from the shores of lakes. This 
sand is similar in properties to the river sand, except that it 
is more likely to consist of rounded, rather than “sharp”, or 
angular grains. 
Bank sand or pit sand is that taken from deposits on land. 
It is liable to contain larger percentages of clay and loam than 
either river or lake sands.