A Visual Encyclopedia of the Periodic Table

146

The Carbon Group

This purple form of

quartz gets its colour

from iron impurities.

This glassy mineral tube

is formed when quartz-rich

sand is struck by lightning.

The pure element

can shatter easily.

Forms

Silicon

Si

14

14 14 14

State: Solid

Discovery: 1824

About 90 per cent of the minerals that make

up Earth’s rocks contain silicon, a common

element in our planet’s crust. Nearly all silicon

minerals are compounds of silicon and oxygen,

known as silicates. The most common silicate is

quartz, the mineral form of silicon dioxide, or

silica. It is also the most common substance in

sand. Amethyst is a type of quartz. Quartz

deposits are widely found in rocks such as granite

and sandstone. A valuable type of silica is opal,

which is used as a gemstone. The clays used to

make pottery and ceramics are also silicates.

Sand

Am

eth

ys

t

Sti

ngi

ng (^) ne
ttle
Sand is mostly tiny
grains of quartz that have
broken away from rocks.
Fulgu
rite
o
f^
p
u
re
s
il
ic
on
La
bo
ra
to
ry
s
am
pl
e
Tiny hairs on these leaves
have silica tips that break
off when you touch them,
releasing chemicals that sting.
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