冰晶石
冰晶石（英語：Cryolite）一种矿物，主要成分为六氟铝酸钠（Na3AlF6），白色单斜晶系（109摄氏度），微溶于水，能溶于氧化铝，在电解铝工业作助熔剂、制造乳白色玻璃和搪瓷的遮光剂。格陵蘭西海岸的伊維圖特（）是冰晶石的主要產地，此矿于1987年开采完毕。现时多以萤石人工合成六氟铝酸钠供工业使用。
| 冰晶石 | |
|---|---|
 Cryolite from Ivigtut Greenland | |
| 基本資料 | |
| 類別 | 鹵化物 |
| 化學式 | 六氟铝酸钠 - Na3AlF6 |
| 施特龙茨分类 | 03.CB.15 |
| 戴納礦物分類 | 11.6.1.1 |
| 晶体空间群 | Monoclinic 2/m |
| 晶胞 | a = 7.7564(3) Å, b = 5.5959(2) Å, c = 5.4024(2) Å; β = 90.18°; Z = 2 |
| 性質 | |
| 分子量 | 209.9 g mol−1 u |
| 顏色 | 無色、黑褐、灰、白、紅褐色 |
| 晶体惯态 | Usually massive, coarsely granular. The rare crystals are equant and pseudocubic |
| 晶系 | 單斜晶系 2/m |
| 雙晶 | Very common, often repeated or polysynthetic with simultaneous occurrence of several twin laws |
| 解理 | 無 |
| 斷口 | 參差狀 |
| 韌性/脆性 | 易脆 |
| 摩氏硬度 | 2.5 to 3 |
| 光澤 | 玻璃，或珍珠光澤 {001} |
| 條痕 | 白色 |
| 透明性 | 透明至半透明 |
| 比重 | 2.95 to 3.0. |
| 光學性質 | Biaxial (+) |
| 折射率 | nα = 1.3385–1.339, nβ = 1.3389–1.339, nγ = 1.3396–1.34 |
| 雙折射 | δ = 0.001 |
| 2V angle | 43° |
| 色散率 | r < v |
| 熔點 | 1012 °C |
| 溶解度 | Soluble in AlCl3 solution, soluble in H2SO4 with the evolution of HF, which is poisonous. Insoluble in water.[1] |
| 其他特徵 | Weakly thermoluminescent. Small clear fragments become nearly invisible when placed in water, since its refractive index is close to that of water. May fluoresce intense yellow under SWUV, with yellow phosphorescence, and pale yellow phosphorescence under LWUV. Not radioactive. |
| 參考文獻 | [2][3][4][5][6] |
使用
冰晶石可用作在霍尔－埃鲁法中還原氧化鋁之電解質，能溶于氧化铝，在电解铝工业作助熔剂，被用于铝的提炼。冰晶石可用作陶瓷、殺蟲劑[7]、研磨料結合劑、電子絕緣、光亮劑等。可由氟化鈉与氟化鋁熔融反应制得。
參考
- CRC Handbook of Chemistry and Physics, 83rd Ed., p. 4-84.
- Gaines, Richard V., et al (1997) Dana’s New Mineralogy, Wiley, 8th, ISBN 978-0-471-19310-4
- Cryolite: Cryolite mineral information and data 页面存档备份，存于. Mindat.org (2010-10-03). Retrieved on 2010-10-25.
- Cryolite Mineral Data 页面存档备份，存于. Webmineral.com. Retrieved on 2010-10-25.
- Cryolite 页面存档备份，存于, Handbook of Mineralogy. Retrieved on 2010-10-25.
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0-471-80580-7
- EPA R.E.D. FACTS Cryolite (PDF). [2011-01-13]. （原始内容 (PDF)存档于2012-10-26）.
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