Compared to most minerals, calcite is not very hard or ... This is always white, regardless of the color of the calcite." Calcite also fluoresces in many different colors under ultraviolet ...

Each type of mineral has a unique crystal structure, which results from its chemical composition and a set of physical properties, such as hardness, color or ... and calcite (CaCO3), can have ...

The fossil may have lost water, or color, or the proteins of the soft tissue may have degraded ... or it may be the growth of larger crystals of an existing mineral such as the large calcite crystals ...