Technically, the term ‘asbestos’ refers to six unique minerals — chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite. Chrysotile (white asbestos) is the most commonly used form of asbestos, while Amosite (brown asbestos) was used most frequently in cement sheets and pipe insulation. Crocidolite (blue asbestos) was commonly used to insulate steam engines, and Anthophyllite, Tremolite, and Actinolite are much less common and rarely found in commercial structures.