Carbonate minerals contain carbonate (C), oxygen (O), plus another element. These minerals tend to be soft, soluble in hydrochloric acid and exhibit a wide array of physical properties. There are around 80 known carbonate minerals, but most of them are rare. Often times, carbonate minerals are found within rock. The carbonate mineral calcite is the main component of rocks formed in ancient seas by organisms such as corals and algae. Common carbonate minerals include aragonite and calcite which are both anhydrous and malachite which is a hydroxide.
