Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). In addition to lead, some deposits contain up to 0.5 percent silver, in the form of silver sulfide or as limited silver in solid solution; when present, this byproduct far surpasses the main lead ore in revenue. Galena has been used since antiquity, one of its oldest uses being the production of kohl, an eye cosmetic now regarded as toxic due to the risk of lead poisoning. In modern times, galena is primarily used to extract its constituent minerals. In addition to silver, it is the most important global source of lead, for uses such as in lead-acid batteries. This sample of galena, measuring 3.5 cm × 2.5 cm × 2.0 cm (1.38 in × 0.98 in × 0.79 in), contains a small amount of gold-colored pyrite and was extracted from the Huanzala Mine in the Peruvian region of Ancash. This photograph was focus-stacked from 156 separate images.Photograph credit: Ivar Leidus