Parts of the teeth include: 1  Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral. 2  Dentine: A layer underlying the enamel. Dentine is made of living cells, which secrete a hard mineral substance.  Pulp: The softer, living inner structure of teeth.
Though they vary significantly, transportation costs accounted for 40% of the average overall cost of coal delivered at electric power plants in 2010. On average, nominal U.S. rail rates for shipping coal grew from $11.83 to $17.25 per short ton from 2001 to 2010.
According to the RHA (Road Haulage Association UK), the average running costs for a single car transporter are: 1  Â£140.00 per working day for depreciation, licensing and insurance. 2  Â£0.22p per mile (approx) running costs (covers fuel, tyres and oil)  Plus the driver's wages....