Dictionary.net

• A grayish white mineral occuring in tetragonal crystals and in cleavable masses. It is essentially a silicate of alumina and soda.

2010 - New Age Dictionary Database
By Oddity Software

• A grayish white mineral occuring in tetragonal crystals and in cleavable masses. It is essentially a silicate of alumina and soda.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.