Graphite (the mineral) consists of parallel sheets of carbon atoms in a hexagonal lattice, which when one or few atoms in thickness, are called graphene. Graphite therefore is made from graphene sheets and there are about 3 million layers of graphene in 1 mm of graphite.
Graphene is everywhere you find graphite however separating graphite to a few atoms thick is expensive and hard to scale up. Main factors delaying uptake include:
• production methods are not scalable enough supply large quantities for commercial uptake
• graphene production is prohibitively expensive
• lower cost scalable production exists however quality limits applications/markets.
Oil is a good analogy to graphene - it is present worldwide however fundamentals are required for commercial success.