Kyanite, andalusite, and sillimanite are anhydrous aluminosilicate minerals that have the same chemical formula, Al₂SiO₅, but differ in crystal structure and physical properties.  When calcined at high temperatures (around 1,350° C to 1,380° C for kyanite and slightly higher for andalusite and sillimanite), these minerals are converted to mullite, 3Al₂O₃·2SiO₂, and silica, SiO₂, which are refractory materials.  In the conversion to mullite, 1 metric ton (t) of mineral concentrate yields about 0.88 t of mullite.  Synthetic mullite is made by heating mixtures of alumina and silica or bauxite and kaolin at around 1,550° C to 2,000° C.  Refractories are heat-resistant materials used in high-temperature applications such as furnaces, boilers, ladles, and kilns, in the metallurgical, glass, chemical, cement, and other industries.

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Annual Publications

Mineral Commodity Summaries

• Kyanite and Related Minerals
    PDF Format:    | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 |2012 |2013 |2014 |2015 |2016 |2017 |2018 | 2019 | 2020 |
• Appendixes

Minerals Yearbook

• Kyanite and Related Minerals
    PDF Format:
      | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 |
    XLS Format:
       | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 tables-only release |
• Archive
       | 1932-1993 |

Special Publications

• Historical Statistics for Mineral and Material Commodities in the United States 
  Data Series 140
  • Kyanite