Messages Archive

Subject:
Interesting
Response To:
Re: True... ()

John in NM
That explains the origin of the terms perhaps. These days the nomenclature is felsic for siliceous rocks and mafic for Mg-Fe rich, silica depleted rocks, intermediate between the two. I haven't heard the acid-base thing since taking a class from a professor who started at U of A when my dad went there :D

I also wonder if this has something to do with how quartz polishes so differently from other silicates.... just speculating of course, but it can be a tricky minderal to polish well. Cerium oxide on plexiglass is how it's typically done, which works well for a lot of silicates, but Alumina on tin works well for just about everything except quartz. Both methods clearly have a chemical action as much or more than abrasive, and it can be seen in what looks like a flow patter on a poorly done facet of quartz.

© 1998 - 2017 by Ellis Walentine. All rights reserved.
No parts of this web site may be reproduced in any form or by
any means without the written permission of the publisher.

WOODCENTRAL, P.O. BOX 493, SPRINGTOWN, PA 18081