Glendon Area

[baehron]

I've been to Glendon twice, and though I like (and have) the pyrite from there, I've wondered what the rocks are that line the parking area (also along road) Steve B. told me someone else was interested in them and took some home to cab. Would love to know what they are, and wouldn't mind seeing examples of the cabbed material. Thanks in advance for any help.

A sample piece from Glendon

[arappaho]

A total Guess; Iron-stained Diabase,
but there is some rhyolite in that area too.
Joe

[baehron]

Thanks Joe, I will research those two mentioned and see if I can't learn more one way or another. The piece in photo doesn't show it much, but besides the obvious colors, there were blues and greens as well.
Kenn

[arappaho]

Well. baehron, after looking at this again I can see I was
way off on my guess. I guess it's just the iron coating you
are trying to ID because the major portion of the rock looks
like the pyrophyllite mined at Glendon. Those "coatings" always
give me a hard time. When is it goethite, hematite, or limonite?
And I can see where this piece may have the irredescent colors
as well.

Joe

[lauriesrocks]

The matrix does look like impure pyrophyllite schist, clearly not diabase, which is very hard dark greenish black and seldom has any hematite coatings. Your piece obviously has coatings of iron oxides, the red color no doubt coming from hematite. Without lab analysis it is very difficult to distinguish between the various iron oxide minerals, such as goethite, hematite. The term limonite is often used as a generic word when these iron oxides are of indefinite composition, but if a red color is present, it indicates the presence of hematite. Way, way too soft for cabbing. Kinda pretty though.

[baehron]

Thanks guys, I appreciate the comments. When I first saw these rocks laying around, some of the colors were quite brilliant and I think moisture changes the look. While I was picking them up, I was quite excited about having a chance to check them out close-up, but when I got them home, I barely recognized them as the same. (Since identifying the pyrite cubes is easy, I knew it must be them, but they don't look the same here as in Glendon. Still like 'em though.