CompuServe Messages

Hi, Doug > Thus an "alkalic igneous intrusion" is a rock sort of like granite in that > it cooled underground and thus has a similar texture, but unlike granite is > short on silica, letting a different suite of minerals dominate. Now I'm confused (so what else is new <g>). I was under the impression that the rocks in the Washington Pass area were alkaline, but I have one specimen that has a couple of smoky quartz micros in a tiny vug. I suppose they could have formed later. The other possibility is that I've been a victim of thread drift (again). Lanny, Help! Regards, Guy