The mineral primarily used for making pencils is graphite. This form of carbon is prized for its ability to leave a mark on paper while being non-toxic and easily erasable. Graphite’s layered structure allows it to slide easily over surfaces, making it ideal for writing instruments. The hardness of graphite can be adjusted by mixing it with clay, leading to various pencil grades ranging from hard to soft. The invention of the modern pencil dates back to the 16th century, and it has remained a popular tool for writing and drawing ever since.