Orange Calcite from Utah is a striking variety of the carbonate mineral calcite (CaCO₃) that displays warm orange to peachy-amber coloration. This colouring is typically caused by trace amounts of iron oxide or other mineral inclusions incorporated during crystal formation.
Orange Calcite is commonly found in sedimentary environments, particularly within limestone and dolomite formations that are abundant throughout Utah’s varied geology. Notable occurrences are associated with hydrothermal veins, vugs (small cavities), and geodes in Paleozoic and Mesozoic sedimentary rocks. The mineral often forms as secondary deposits where calcium-rich groundwater has circulated through fractures and cavities, allowing calcite crystals to precipitate slowly over time.
With a hardness of 3 on the Mohs scale, orange calcite is relatively soft and will effervesce readily in dilute hydrochloric acid—a diagnostic test for carbonate minerals.
