alkali-lime index

alkali-lime index

[′al·kə‚lī ′līm ‚in·deks]

(petrology)

The percentage by weight of silica in a sequence of igneous rocks on a variation diagram where the weight percentages of CaO and of K₂ O and Na₂ O are equal.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.