Orange Calcite

Orange calcite is a popular coloured variant of the common mineral, calcite. A common carbonate mineral, regarded as a polymorph of calcium carbonate (with aragonite being another), these specimens exhibit a rich orange colouration and instead have a microcrystalline structure as opposed to the large calcite rhombs often seen that we also stock. This means that the individual calcite crystals are too small to be seen with the naked eye, they tightly interlock with each other to form a larger mass. As expected from minerals of this family, it is very soft, coming in at number 3 on the Mohs scale of hardness and can be distinguished by performing an acid test (hydrochloric acid in laboratory conditions) to observe the calcite crystals reactions which causes it to bubble and fizz. Calcite occurs natural and is quite common in sedimentary rocks as either a cement or as crystals, particularly limestone, of which it is the main constituent. The colouration of orange calcite is due to the inclusion of microscopic crystals of hematite (iron oxide), an iron mineral well known for it’s deep red colour, the amount of which will effect the vibrancy of the overall colour. It is the light reflecting off of these minute crystals which makes us see the mineral as orange in colour (or shades of). It has long been used as a decorative gemstone, albeit not as much as other minerals, but due to its soft nature, it can be carved into many shapes and sizes in a fairly short space of time. These particular pieces come from Mexico and are available in various sizes, they are ideal for collectors, young and old alike, enthusiast and educational use to depict the various crystal habits and colours which a mineral (calcite in this case) can take. Each sample will come supplied in a card tray with an information label.