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A metallic element found in certain rare minerals, as thorite, pyrochlore, monazite, etc., and isolated as an infusible gray metallic powder which burns in the air and forms thoria; -- formerly called also thorinum. Symbol Th. Atomic weight 232.0.

A radioactive product intermediate between thorium and radiothorium, with a period of 5.5 years.

A radioactive substance apparently formed as a product from thorium.

A rare mineral, containing chiefly niobium, titanium, thorium, and cerium. It was so called by Berzelius on account of the inability of chemical science, at the time of its discovery, to separate some of its constituents.

A rare white earthy substance, consisting of the oxide of thorium; -- formerly called also thorina.

Of or pertaining to thorium; designating the compounds of thorium.

ack color, or, as in the variety orangite, orange-yellow. It is essentially a silicate of thorium.

A mineral consisting chiefly of uranium oxide with some lead, thorium, etc., occurring in black octahedrons, also in masses with a pitchlike luster; pitchblende.

rare element supposed by Bahr to have been extracted from wasite, but now identified with thorium.

thoria and ceria. The mantle is made by soaking a "stocking" in a solution of nitrates of thorium and cerium (approx. 99 : 1), drying, and, for use, igniting to burn the thread and convert the nitrates into oxides, which remain as a fragile ash. The light far exceeds that obtained from the same amount of gas with the o…