Rock wool

Mineral wool is a general name for fiber materials that are formed by spinning or drawing molten minerals (or "synthetic minerals" such as slag and ceramics).

Applications of mineral wool include thermal insulation (as both structural insulation and pipe insulation, though it is not as fire-resistant as high-temperature insulation wool), filtration, soundproofing, and hydroponic growth medium.

Mineral wool is also known as mineral fiber, mineral cotton, mineral fibre, man-made mineral fibre (MMMF), and man-made vitreous fiber (MMVF).

The nomenclature of these wool products is simply the parent/raw material name in prefix to "wool". Specific mineral wool products are stone wool and slag wool. Europe also includes glass wool which, together with ceramic fiber, are completely man-made fibers.

Slag wool was first made in 1840 in Wales by Edward Parry, "but no effort appears to have been made to confine the wool after production; consequently it floated about the works with the slightest breeze, and became so injurious to the men that the process had to be abandoned". A method of making mineral wool was patented in the United States in 1870 by John Player and first produced commercially in 1871 at Georgsmarienhütte in Osnabrück Germany. The process involved blowing a strong stream of air across a falling flow of liquid iron slag which was similar to the natural occurrence of fine strands of volcanic slag from Kilauea called Pele's hair created by strong winds blowing apart the slag during an eruption.

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Wikipedia