蓝晶石

蓝晶石
蓝晶石
基本资料
类别	岛硅酸盐矿物
化学式	Al2SiO5
IMA记号	Ky
施特龙茨分类	9.AF.15
晶体分类	平行双面(1) ; （H-M记号相同）
晶体空间群	P1
晶胞	a = 7.1262(12) Å ; b = 7.852(10) Å ; c = 5.5724(10) Å ; α = 89.99(2)°, β = 101.11(2)° ; γ = 106.03(1)°; Z = 4
性质
颜色	蓝色、白色，少见绿色、灰色、黄色、粉色、橙色和黑色
晶体惯态	柱状；纤维状；刀刃状
晶系	三斜
双晶	{100}层状
解理	[100]完全 [010]不完全
断口	参差状
韧性/脆性	脆
莫氏硬度	4.5-5（平行于轴）; 6.5-7（垂直于轴）
光泽	玻璃光泽
条痕	白色
透明性	透明到半透明
比重	3.53 - 3.65（测量）；3.67（计算）
光学性质	双轴 (-)
折射率	nα = 1.712 - 1.718 nβ = 1.720 - 1.725 nγ = 1.727 - 1.734
多色性	三色，无色-淡蓝色-蓝色
2V夹角	78°-83°
参考文献

蓝晶石（英语：Kyanite）是一种典型的蓝色含铝硅酸盐矿物，存在于富含铝的变质伟晶岩和沉积岩中。变质岩中的蓝晶石通常表明压力高于4千巴。它通常能在石英中发现。尽管在较低的压力和低温下可能稳定，但水的活性通常足够高，以至于可被其他水合硅酸铝（如白云母、叶蜡石或高岭石）取代。

蓝晶石是硅酸铝系列的成员，其中还包括多晶型红柱石和多晶型硅线石。蓝晶石具有很强的各向异性，其硬度取决于其晶体学方向。对于蓝晶石来说，这种各向异性可以被认为是一种识别特征。

温度高于1100 °C的蓝晶石通过以下反应分解为莫来石和熔凝石英：

3(Al₂O₃·SiO₂) → 3Al₂O₃·2SiO₂ + SiO₂

这种转变导致了膨胀。^[5]

它的名称与青色的起源相同，源自古希腊语κύανος。通常以kyanos或kuanos的形式翻译成英文，意为“深蓝色”。

识别

蓝晶石的细长的柱状晶体通常是矿物及其颜色（标本为蓝色时）的良好提示。伴生矿物也非常有用，尤其是多晶型十字石。识别蓝晶石最有用的特征是各向异性。如果怀疑样品是蓝晶石，识别的关键是在垂直轴上具有两个截然不同的硬度。平行于{001}的硬度为5.5，平行于{100}的硬度为7。^[2]^[3]

发现

蓝晶石

红柱石

硅线石

Al₂SiO₅（硅酸铝）的相图^[6]

蓝晶石出现在片麻岩、片岩、伟晶岩和石英矿脉中，主要是由泥质岩的高压区域变质引起的。 ^[7]它以碎屑的形式出现在沉积岩中。它的出现与十字石、红柱石、硅线石、滑石、角闪石、直闪石、莫来石和刚玉有关。 ^[2]

蓝晶石出现在曼哈顿片岩中，这是由于形成盘古大陆的两个大陆而在极高的压力下形成的。 ^[8]

用途

蓝晶石主要用于耐火材料和陶瓷产品，包括陶瓷水暖和餐具。也用于电子产品、绝缘体和磨料。蓝晶石已被用作半宝石，它可能会显示出猫眼效应，尽管由于它的各向异性和完美切割而受到限制。颜色品种包括最近从坦桑尼亚发现的橙色蓝晶石。 ^[9]橙色是由于结构中含有少量锰（Mn³⁺）所致。 ^[10] 蓝晶石是用于评估岩石变质的温度、深度和压力的一种指标矿物。

参考资料

^ Warr, L.N. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 2021, 85 (3): 291–320 [2022-10-30]. Bibcode:2021MinM...85..291W. S2CID 235729616. doi:10.1180/mgm.2021.43. （原始内容存档于2021-11-19）.
^ ^2.0 ^2.1 ^2.2 Kyanite (PDF). Handbook of Mineralogy. 2001 [2018-01-01]. （原始内容 (PDF)存档于2019-05-08）.
^ ^3.0 ^3.1 Kyanite. MinDat. [2013-06-14]. （原始内容存档于2012-08-03）.
^ Kyanite Mineral Data. Webmineral.com. [2013-06-14]. （原始内容存档于2020-01-19）.
^ Speyer, Robert. Thermal Analysis of Materials. CRC Press. 1993: 166 [2021-04-30]. ISBN 0-8247-8963-6. （原始内容存档于2021-04-30）.
^ Whitney, D.L. Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al₂SiO₅ polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey. American Mineralogist. 2002, 87 (4): 405–416. doi:10.2138/am-2002-0404.
^ Geology Page - Kyanite. Geology Page. 2014-05-16 [2020-02-20]. （原始内容存档于2021-05-02）.
^ Quinn, Helen. How ancient collision shaped New York skyline. BBC Science. BBC.co.uk. 6 June 2013 [2013-06-13]. （原始内容存档于2013-06-13）. Prof Stewart was keeping an eye out for a mineral known as kyanite, a beautiful blue specimen commonly seen in the Manhattan schist. 'Kyanite is a key mineral to identify, we know it only forms at very deep depths and under extensive pressure,' he said. 'It's like a fingerprint, revealing a wealth of information.' The presence of this mineral reveals that the Manhattan schist was compressed under incredibly high pressure over 300 million years ago. The schist formed as a result of two enormous landmasses coming together to form a supercontinent, known as Pangaea.
^ M. Chadwick, Karen; R. Rossman, George. Orange kyanite from Tanzania. Gems and Gemology. 2009-01-01, 45 [2021-04-30]. （原始内容存档于2021-05-02）.
^ M. Gaft; L. Nagli; G. Panczer; G. R. Rossman; R. Reisfeld. Laser-induced time-resolved luminescence of orange kyanite Al₂SiO₅. Optical Materials. August 2011, 33 (10): 1476–1480. Bibcode:2011OptMa..33.1476G. doi:10.1016/j.optmat.2011.03.052.

拓展阅读

Mineral Galleries
Faye, G. H.; Nickel, E. H. On the origin of colour and pleochroism of kyanite (PDF). The Canadian Mineralogist. 1969, 10: 35–46 [2021-04-30]. （原始内容 (PDF)存档于2020-07-24）.

外部链接

Cyanite. Encyclopædia Britannica (第11版). London. 1911.

[1] Warr, L.N. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 2021, 85 (3): 291–320 [2022-10-30]. Bibcode:2021MinM...85..291W. S2CID 235729616. doi:10.1180/mgm.2021.43. （原始内容存档于2021-11-19）.

[Handbook-2] 2.0 ^2.1 ^2.2 Kyanite (PDF). Handbook of Mineralogy. 2001 [2018-01-01]. （原始内容 (PDF)存档于2019-05-08）.

[Mindat-3] 3.0 ^3.1 Kyanite. MinDat. [2013-06-14]. （原始内容存档于2012-08-03）.

[Webmin-4] Kyanite Mineral Data. Webmineral.com. [2013-06-14]. （原始内容存档于2020-01-19）.

[5] Speyer, Robert. Thermal Analysis of Materials. CRC Press. 1993: 166 [2021-04-30]. ISBN 0-8247-8963-6. （原始内容存档于2021-04-30）.

[6] Whitney, D.L. Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al₂SiO₅ polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey. American Mineralogist. 2002, 87 (4): 405–416. doi:10.2138/am-2002-0404.

[GeologyPage-7] Geology Page - Kyanite. Geology Page. 2014-05-16 [2020-02-20]. （原始内容存档于2021-05-02）.

[8] Quinn, Helen. How ancient collision shaped New York skyline. BBC Science. BBC.co.uk. 6 June 2013 [2013-06-13]. （原始内容存档于2013-06-13）. Prof Stewart was keeping an eye out for a mineral known as kyanite, a beautiful blue specimen commonly seen in the Manhattan schist. 'Kyanite is a key mineral to identify, we know it only forms at very deep depths and under extensive pressure,' he said. 'It's like a fingerprint, revealing a wealth of information.' The presence of this mineral reveals that the Manhattan schist was compressed under incredibly high pressure over 300 million years ago. The schist formed as a result of two enormous landmasses coming together to form a supercontinent, known as Pangaea.

[9] M. Chadwick, Karen; R. Rossman, George. Orange kyanite from Tanzania. Gems and Gemology. 2009-01-01, 45 [2021-04-30]. （原始内容存档于2021-05-02）.

[10] M. Gaft; L. Nagli; G. Panczer; G. R. Rossman; R. Reisfeld. Laser-induced time-resolved luminescence of orange kyanite Al₂SiO₅. Optical Materials. August 2011, 33 (10): 1476–1480. Bibcode:2011OptMa..33.1476G. doi:10.1016/j.optmat.2011.03.052.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]