Slate (writing)

[1] Split slate was prepared by scraping with a steel edge, grinding with a flat stone and, finally, polishing with a mix of slate powder in water.

Pencils were of a softer stone, such as shale, chalk or soapstone.

[2] In 1853 Charles Goodyear patented a compound of hard-vulcanised rubber with powdered porcelain, from which to make white pencils for writing on slates.

At the dawn of the twentieth century, writing slates were the primary tool in the classroom for students.

The writing slate was sometimes used by industry workers to track goods and by sailors to calculate their geographical location at sea.