Algodonite is a rare mineral made mainly of copper and arsenic (Cu₆As). It forms in hydrothermal environments, usually near copper ore deposits. The mineral was first discovered in Chile’s Algodones mining district. It has a metallic luster with a grayish-white to silver-gray color. Algodonite is opaque and does not show brilliance like typical gemstones. It is relatively soft (Mohs hardness around 3) and quite dense. Due to arsenic content, it can be hazardous and must be handled carefully. Although not used in jewelry, it is valuable for collectors and scientific study.