Structure of Sillimanite and Related Materials
JSGT 1932 V16 T111-T120
The paper gives an account of the present state of our knowledge of the structures of alumino-silicates used in technical processes. The structures of the three naturally occurring forms of Al2SiO5 are described and it is shown that the co-ordination-number of corresponding aluminium atoms is 4, 5, and 6 in sillimanite, andalusite, and cyanite, respectively. It is probable that mullite differs from sillimanite only in the substitution of one SiO4 group (in sillimanite) by one AlO4 group (in mullite), together with a slight adjustment of the number of oxygen atoms required to balance valencies. Other related structures probable occur in porcelains.
W. H. Taylor
