Diamond is made up of only one element, carbon, and the arrangement of the C atoms in the lattice gives diamond its incredible capabilities. Carbon has two common forms: graphite and diamond. Graphite is formed when many layers of graphene (a single layer of carbon atoms bonded together) roll into balls that can be found at the center of some pencil leads. Diamond is only found in nature inside living things. It is the most abundant mineral in the earth's crust, which means it is found everywhere on Earth except in space. Like other carbon allotropes such as carbon nanotubes and fullerenes, diamond has great strength but is soft. It is the hardest substance known to man. The depth of a diamond's color depends on how much nitrogen it contains. Colorless diamonds are usually called "white diamonds." They account for less than 1% of all diamonds. The rest are colored from light yellow to dark red. The average density of diamond is 3154 kg/m3 while that of graphite is 3005 kg/m3. Thus, diamond is more dense than graphite. There are two types of bonding in diamond: covalent and ionic. In covalent bonding, each atom shares electrons with its neighboring atoms so they cannot escape.