Mineral wool and glass wool are made from slag, rock, glass, and minerals that have been melted and spun into filaments. Mineral wool and glass wool is frequently used as thermal insulation and as a fireproofing material because the fibers are non-combustible and have very high melting temperatures.

Mineral wool and glass wool products are made from the spun fibers of slag, rock, and glass materials that have been melted or fused. Glass wools are typically made from a fused mixture of sand and recycled glass materials. The glass wool traps air, which makes it an ideal insulation material against heat, cold, and noise. Because it is also flexible, elastic, and lightweight, glass wool is relatively easy to install.

Mineral wool and glass wool products include those made from heating slag or stone. Mineral wools are made by blowing a stream of air or steam through molten rock. Other techniques for producing rock wool include spinning the molten rock on high speed wheels to produce a type of floss. Mineral wool or stone wool may also contain a binding compound and oil to minimize dust and make the mineral wool water repellent.

Mineral wool and glass wool are poor conductors of heat and sound, making them both good insulators. They are fire-proof and insect-proof, making them useful in construction applications. Mineral wool and glass wool are also used as filtering products in laboratory applications. Mineral wools in particular are also used in automotive gaskets and brake pads, in plastics and even as a growth medium in hydroponic applications. Mineral wool is useful in hydroponics because it can simultaneously hold water and air, encouraging the roots to grow and providing the plant a good structure to support it while it grows. However, mineral wool used in hydroponic applications must be specially conditioned to moderate its high pH, which can be detrimental to the plant over time.