1 kilo of blue Calcite mineral specimens, showing typical cubic cleavage and vitreous/pearly lustre. Calcite is a common and widespread mineral with variable forms and colours, best recognised by its relatively low Mohs hardness (3) and its high reactivity with even weak acids: e.g. vinegar, along with its prominent cleavage in most varieties. It is possible that the blue colouration of this mineral is from copper impurities which often turns a hue of green or blue when it oxidises. These mineral specimens are ideal for schools, educational and teaching use, specimens are supplied are a range of sizes, varying between 20 mm and 80 mm and come in a strong polythene bag by kilo weight, also supplied is a small information card. Excellent for when bulk quantities are required.