Crocidolite

Crocidolite, also known as blue asbestos, is an asbestos mineral in the amphibole group. It forms as elongated, fibrous crystals that readily separate into thin, durable fibers, which can be inhaled and become lodged in the lungs. Chemically, crocidolite is a sodium iron silicate hydroxide with iron present in multiple oxidation states, giving its characteristic blue color. It occurs in metamorphosed iron-rich rocks and in hydrothermal veins, and has been mined in several countries. Historically, crocidolite was used for insulation, fireproofing, cement products, and other building materials because of its resistance to heat and its fibrous strength. In many jurisdictions its use has been banned or severely restricted because of health concerns.

Health and regulation: Crocidolite is a highly hazardous form of asbestos. Inhalation of its fibers is linked to serious diseases such as asbestosis, lung cancer, and malignant mesothelioma. Because of these risks, crocidolite-containing materials are tightly regulated and removal is performed by trained professionals under protective measures. Regulations vary by country, but bans and strict controls are common worldwide.