Calcite rhomb mineral specimens which depict the calcite crystal perfectly in its natural rhombic crystal form, these pieces have not been cut or polished in anyway and come as they are. Calcite is one of the polymorphs of calcium carbonate, the others being aragonite and vaterite. Calcite is one of the index minerals in the Mohs scale at number 3, as it is a fairly soft mineral, able to be scratched by your finger nail. As expected of this group of minerals, it reacts with hydrochloric acid or vinegar to release bubbles of CO2, this causes a reactions which results in bubbling and fizzing on the surface of the specimen. This can prove a useful identification method in the field when calcite is in a more massive form, or as an enjoyable teaching aid under laboratory conditions. The rhomb crystals in these specimens are large and well formed, however, as they are natural, not cut and not polished, small chips and scratches will be visible. The pieces are available in two colours, red or white as well as a range of sizes. They were collected from Morocco and will be supplied in a labelled card tray.