The chemical lead was used by the Romans as lead rods to write on papyrus. These rods left a grey mark just like graphite. Hence, graphite was believed to be a type of lead. In 1564 a graphite deposit was discovered in England, which led to its widespread use for writing. The lead used in pencils are not actually the chemical lead but graphite and clay. An average pencil can write about 45,000 words, or a line about 35 miles (56 km) long.
Which chemical is used in the lead of a pencil?
