Some
natural graphites, often in the form of large flakes, show very high
crystalline perfection. Occasionally, they occur as single crystals
of
graphite.
The use of the
term natural
graphite as a synonym for the term '
graphite single
crystal' is incorrect and should be avoided. Varieties of natural
graphite with lower structural perfection are classified as
'
microcrystalline natural graphite'. Commercial natural
graphite is
often contaminated with other minerals, e.g. silicates, and may
contain
rhombohedral graphite due to intensive
milling.