bituminite is commonly found in the size and shape of irregular, discoidal particles that are typically 100-200 μm in diameter. when observed under transmitted light with oil immersion, the color of bituminite is orange, reddish to brown. under reflected light, bituminite is dark brown to dark grey and sometimes black in color. bituminite has an approximate density of ≈1.2-1.3 g/cm, which was determined by gradient centrifuging. bituminite has a very low polishing hardness. it usually smears during the polishing process because it is unconsolidated and very soft.