(n). Geology. [K1-1. 5Al4(Si7-6. 5Al1-1. 5O20)(OH)4] A group of clay minerals formed during the alteration of silicate mineralssuch as mica and feldspar andcommonlyfound in marine shales. See: shale
Schlumberger Ltd. (The World's Leading Supplier Of Technology, Integrated Project Management And Information Solutions to Customers Working in The Oil and Gas Industry Worldwide), Schlumberger Oilfield Glossary Cedex, France 2014. http://www.glossary.oilfield.slb.com/en/Terms/sym/ a.aspx, (Ergo - Brit) {766}