Your pencil's black core is called lead. But it has no lead in it. It is graphite. People once thought graphite was a kind of lead, so they called it black lead. We still say pencil lead today.
In 1779, scientists showed that the core was carbon. About ten years later it got the name graphite. The name comes from a Greek word that means to write. Graphite is made of tiny layers of carbon. The layers slide apart, so a pencil leaves a line.
Diamond is made of carbon too. Graphite and diamond look and feel very different. In the 1500s, graphite was found near Borrowdale in England. It became the first big graphite mine.
In the 1790s, a French engineer named Nicolas-Jacques Conté found a new way to make cores. He mixed graphite with clay and baked it. The more clay in a core, the harder the pencil. The more graphite, the softer and darker it is.
Many pencils are made from cedar wood. Cedar smells nice and does not warp. Makers cut grooves in boards and lay graphite sticks in them. Then they glue a second board on top and cut it into pencils.
A pencil's hardness is shown by a number or letters. A No. 1 pencil is the softest. A No. 2 pencil is the one used for most writing.
Words to know
- graphite: soft black mineral
- carbon: an element
- engineer: skilled builder
- cedar: tree wood
