Marble rock can be either
regional or contact metamorphic rock.
That means it can form
by rising temperatures and pressures, or by heat only.
The main mineral it
consists of is calcite
(there is also a dolomitic version that consists of dolomite).
minerals - impurities - include quartz,
More rarely sphene, tourmaline, epidote, zoisite, spinel,
garnet, albite, labradorite, tremolite and/or diposide can also be
So unless it's white and consists of calcite only, some
impurities are giving it a different colour.
By Par_e via Flickr.com
It is formed at
and low to high pressures.
philaLAB via Flickr.com
It has a
structure and it is soft, much softer than quartz, which can look
similar. It has a fine to coarse texture.
David Fielding via Flickr.com
It forms from limestone
(or dolomite - the dolomitic version).
Bryan Lee via Flickr.com
It is easy to distinguish from
quartz by trying its softness or testing it with HCl - it reacts to the
Wally Gobetz via Flickr.com
Due to its softness
perfect to sculpture and has
been sculptured since ancient times.
Bart Everson via Flickr.com
It is also widely used in
buildings and countertops, tabletops etc.
Quinn Dombrowski via Flickr.com
A famous building built from
marble is Taj Mahal in India.