Slagk

Slagk is a term used in geology and industrial metallurgy to describe a glassy, slag-derived material that resembles natural glass but originates from metallic byproducts. The term is not formally recognized as a mineral species by major databases, and its use varies between disciplines; some authors apply slagk to natural glass formed from quenched slag, while others use it for synthetic glasses produced from slag compositions.

They typically contain iron and silica-rich matrices, with aluminum oxide and trace metals from the original alloy. The material is vitreous, often dark brown to black, with a glassy luster and a conchoidal fracture. Hardness is commonly about 5–6 on the Mohs scale, and density ranges from 2.8 to 3.3 g/cm3, depending on oxide content. Inclusions may include metallic droplets and oxide crystals such as magnetite or fayalite.

Formation and occurrence: Natural slagk-like glass can form when molten slag is rapidly cooled and quenched, such as in slag heaps or abandoned smelting sites. It can also occur in geological settings that modify slag deposits through hydrothermal processes or volcanic action.

Uses and significance: Slagk is of interest in archaeometallurgy as an indicator of past metalworking activity, and in materials science for studying slag crystallization. It is sometimes collected as a decorative glassy material, and in field settings it may be confused with obsidian or fulgurite.