So long as the abundant Canadian material is accessible on reasonable conditions, the United States is about as well situated as if independent. Some Canadian proposals of restriction during the war led to a study of other supplies and showed that several deposits, such as those in Russia and Africa, might compete with the Canadian asbestos. GEOLOGIC FEATURES Asbestos consists mostly of magnesium silicate minerals--chrysotile, anthophyllite, and crocidolite. The term asbestos covers all fibrous minerals with some tensile strength which are poor conductors and can be used for heat-protection. Like talc, they are derived principally from the alteration of olivine, pyroxene, and amphibole,--or more commonly from serpentine, which itself results from the alteration of these minerals. Chrysotile is the most common, and because of the length, fineness, and flexibility of its fibers, enabling it to be spun into asbestos ropes and fabrics, it is the most valuable. Anthophyllite fibers, on the other hand, are short, coarse, and brittle, and can be used only for lower-grade purposes. Crocidolite or blue asbestos is similar to chrysotile but somewhat inferior in fire-resisting qualities. Asbestos deposits occur chiefly as veinlets in serpentine rock, which is itself the alteration of some earlier rock like peridotite. They are clearly formed in cracks and fissures through the agency of water, but whether the waters are hot or cold is not apparent. The veinlets have sometimes been interpreted as fillings of contraction cracks, but more probably are due to recrystallization of the serpentine, proceeding inward from the cracks. In Quebec the chrysotile asbestos (which is partly of spinning and partly of non-spinning grade) forms irregular veins of this nature in serpentine, the fiber making up 2 to 6 per cent of the rock. In Georgia the asbestos, which is anthophyllite, occurs in lenticular masses in peridotite associated with gneiss. It is supposed to have formed by the alteration of olivine and pyroxene in the igneous rocks. In Arizona chrysotile is found in veins in cherty limestone, associated with diabase intrusives. Here it is believed to be an alteration product of diopside (lime-magnesia pyroxene) in a contact-metamorphic silicated zone. Crocidolite is mined on a commercial scale only in Cape Colony, South Africa. The deposits occur in thin sedimentary layers interbedded with jaspers and ironstones. Their origin has not been worked out in detail. The deposits of Russia, the Transvaal, Rhodesia, and Australia are of high-grade chrysotile, probably similar in origin to the Quebec deposits. The asbestos of Italy and Cyprus is anthophyllite, more like the Georgia material. BARITE (BARYTES) ECONOMIC FEATURES