Saturday, November 14, 2009

11-14-09 Iron Oxide

Keith W. sent me an email to ask a really good question about rocks he saw along the Little River (which is where I took this photo) on the North Twin Trail that looked just like someone had come along with a can of paint and painted them this red-brown color. When I was a rookie and asked that question all I got was a brusque "iron oxide".

At a reunion dinner last Saturday night in Crawford Notch of all former and present hut croo, living and dead, I asked geologist Thom Davis for a more comprehensive explanation and he said: "Iron (red-brown) oxides stain just about anything, but especially quartz-rich rocks (the quartz crystal lattice picks up all kinds of colors; think about all the varieties of quartz, such as pink, smoky, amethyst, milky, etc.). The red-colored bedrock in the Whites that I usually use as an example is "Red Rocks" on the Old Bridle Path (on Mt. Lafayette), which is a felsite (quartz rich) dike (not basalt, or diabase, as is the Black Dike at the south end of Cannon Cliffs."

Thanx Keith & Thom

1 comment:

Keith said...

Thanks Alex for looking into this for me. They truly do look painted.

Keep up the great work. Love the blog. It's becoming a regular stop on the interwebs for me.