The Christensen Sillimanite Deposit Southeast of Dillon, Montana

The minerals sillimanite, kyanite, andalusite, dumortierite, and topaz comprise a group of minerals whose high alumina content and physical properties are particularly desirable in the manufacture of refractory products. Sillimanite is the least plentiful of the minerals of this group, and for this reason it is not used extensively at the present time. However, it would be very desirable to the refractory industry if a suitable domestic source of supply could be established.