Title: Cryolite
CAS Registry Number: 15096-52-3
Additional Names: Kryolith; ice spar; sodium aluminum fluoride
Molecular Formula: AlF6Na3
Molecular Weight: 209.94
Percent Composition: Al 12.85%, F 54.30%, Na 32.85%
Line Formula: 3NaF.AlF3
Literature References: A mineral named for its resemblance to ice; large deposits existed in Greenland and in the Urals. Synthetic cryolite is usually made from NaAlO2, NaHCO3 and NaF. See the review by Vogel, Chem. Ztg. 75, 603 (1951).
Properties: Snow-white, semi-opaque masses, vitreous fracture. Monoclinic crystals with cubic habit, perfect cleavage (001) (110) (101). The natural form may be colored reddish or brown or even black, but loses this discoloration on heating. d 2.95. Mohs' hardness 2.5-3. Fuses fairly easily, mp 1000°. Sol in concd H2SO4. Dec by boiling with aq alkali hydroxides or aq calcium hydroxide.
Melting point: mp 1000°
Density: d 2.95
CAUTION: Potential symptoms of overexposure are irritation of eyes and respiratory system; nausea, abdominal pain, diarrhea; salivation, thirst and sweating; stiff spine; dermatitis; calcification of ligaments of ribs and pelvis. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 280. |