A massive piece of Graphite easily marks paper, as well as your hands.
CHEMISTRY C Carbon
CRYSTALLOGRAPHY Hexagonal
CRYSTAL GROWTH AND HABITS Graphite is common as hexagonal or scaly plates and is also massive.
COLOR AND OTHER OPTICAL PROPERTIES Iron black to steel gray
HARDNESS 1 - 2
SPECIFIC GRAVITY 2.1 - 2.2
LUSTER Submetallic to metallic or oily
STREAK Black to steel gray
BREAKABILITY Perfect basal cleavage. In the process of touching graphite, cleavage planes are separated allowing the graphite to "soil" your hands. It is this ease of cleavage that allows graphite to be used as a non volatile lubricant.
OCCURRENCE Graphite is formed by the metamorphism of carbonaceous sedimentary rocks like coal.