Description
Magnesite is an ivory-white mineral composed of magnesium, carbon, and oxygen. Its chemical formula is MgCO3. Beautiful specimens are difficult to find and are highly sought after by collectors. Magnesite owes its name to its main component, magnesium. Magnesium is a naturally occurring element. The mineral occurs in solid, opaque, microcrystalline masses, resembling porcelain. It has a predominant color, usually grayish or yellowish white. In well-formed crystals, magnesite is colorless and transparent when pure. It is grayish-yellow or yellowish-white, and sometimes merely translucent when it contains impurities. These are elements such as iron, manganese, or calcium, which partially replace the magnesium in the mineral. In ultraviolet light, the crystals exhibit a strong greenish-white or blueish-white fluorescence. Magnesite is often confused with calcite. A reliable identification method is the hydrochloric acid test: if a few drops of dilute acid fizz on the mineral, it is calcite. Iron is an element that often replaces part of the magnesium in magnesite crystals. This does not alter the mineral's crystal structure. Consequently, many possible compositions exist in nature, ranging from pure magnesite (magnesium carbonate) to siderite (iron carbonate). Once the mineral contains more than 50% iron carbonate, it is considered siderite. There are essentially three stages: pure magnesite, yellow magnesite, and siderite. Pure magnesite contains colorless, transparent crystals, indicating that the mineral does not contain iron. Yellow magnesite has a yellow color and indicates a relatively high iron content. Siderite contains more than 50% iron and is therefore no longer considered magnesite. Magnesite forms in various environments. It results from the transformation of igneous and metamorphic rocks. It generally forms massive deposits. The richest deposits of magnesite are located in Spain. Other countries where magnesite is commonly found are Brazil, Italy, Austria, Poland, and Russia.
Magnesite
