The writer believes that the process of albitization, now known to be a common accompanying feature of granitic intrusion, furnishes a key to the genesis of alkaline rocks. The passage of emanations rich in soda and alumina, which albitization phenomena show have occurred, may in favorable instances have desilicated a granitic magma and so enriched it in soda and alumina that nephelite would crystallize, and after consolidation, soda-rich deuteric minerals form.