E. D. Clarke was the first mineralogist by whom crystallised graphite was observed and examined. As early as 1821, he described some graphite crystals from the mines at Borrowdale, in Cumberland. Clarke designated graphite by the name of " carburet of iron" or "plumbago," and stated its form to be that of an oblique four sided prism, the obtuse angle of which was found by measurement with the contact goniometer (" the common goniometer ") to be 118°.