Specimens of fluorite with minute amounts of pyrobitumen crystals from Ashover, Derbyshire, UK. Fluorite is a popular mineral specimen for many, children, teachers, collectors etc, it often forms with a cubic crystal habit with the crystals being a variety of colours and sizes from deep rich purples, vibrant greens, calming yellows and sometimes crystal clear. These pieces of fluorite have minute amounts of pryobitumen crystals upon their surface, the pyrobitumen crystals have a amorphous form and are black in colour. Pyrobitumen is a mostly insoluble hydrocarbon mineraloid, it is formed by the polymerisation of petroleum and as such is related to petroleum in the same way that amber is related to tree resin. These samples are great for smaller mineral collections and collectors of British minerals. Specimens are supplied in a white card tray with an information label.