CompuServe Messages

Hi Guy! I've been out of sink for a while (Montana Rendezvous the 30th-1st, then immediately off to Utah [Thomas Range] for a full week, home a couple days then back to Montana to look at my new natrolite locality [in the first winter storm for the season]) but am home again, at last. As you probably note from the other messages in this thread that in the "alkalic" and similar terms we are talking about various degrees of alkaline/acid. There are few absolutes. An alkaline intrusive rock is loaded with Na, K, Ca, and short on SiO2. An alkaline granite has to have SiO2 (quartz) or it isn't a granite, so an alkaline granite like the one at Washington Pass, WA is about the same a s a "regular" granite, except it has more Na and K than is necessary to make the feldspars, so it is on the alkaline side, but not really an alkaline intrusive rock. As a granite, it still has quartz grains in the rock and typically quartz crystals in the cavities. Lanny