FMF - Friends of Minerals Forum, discussion and message board

[Bob Harman]

As most field collectors know, iron oxides are so pervasive and common that many many collected mineral specimens have some degree of rusty iron staining. Trying to clean and improve the mineral specimens with various rust removing solutions meets with varying success. Some mineral specimens can be meaningfully improved, while most examples cannot.

Over the years, I tried to deal with this and came up with the idea of developing a reference collection of Indiana specimens that show the wide range of staining shades and colors. By themselves many of my examples are of low quality, but combining those, of the many shades, with more or less aesthetic stains gave me a nice reference collection. Most of these will eventually go to the Indiana State Museum to be added to their collections of Indiana specimens.

Here are some photos. Enjoy, Bob

[Bob Morgan]

A question:
On any of your quartz lined geodes are there any that have three major rhomb faces for terminations of the quartz crystals and smaller minor rhombohedral 'gables' toward the base of the major rhomb faces?
Some like that are found in Keokuk geodes. I'm curious how common that habit might be. in other localities, like maybe in Indiana.

[Bob Harman]

HI Bob and Happy New Year to you!

If your question is referring to the so called pseudocubic variant of the druzy quartz crystal tips discussed in a February 2018 article in Rock & Gem periodical, yes, they are quite common over here in Indiana.
They are often overlooked as most of the examples are found in lower end ordinary quartz geode examples.

I have several, including one previousy pictured on pg. 2 of this thread. I have reposted the example here. Look in the lower left of the cavity to see the best area. The small Malchite is very rare here and the reason I kept that geode.
I'll take a photo of another better example and post it within a day or so.

If you are referring to something else let me know and we will go from there. BOB

[Bob Harman]

Bob, Here is another of my pseudocubic Quartz specimens.

Aragonite or Kaolinite coats the Quartz crystal tips. In this rather small cavity, there also is Smoky Quartz crystal groupings, making for a diamond dewdrop variant of this geode.

[Bob Morgan]

I think I see some of the Dauphiné twinning. In the attached photo the red arrows point to small minor rhombohedral ridges in a Dauphiné relationship to the major rhombohedral pseudocubes. The yellow arrows point to two side by side crystals in the Dauphiné 180 degree rotation from each other.
There are a few on mindat from Keokuk and others have been reported from Germany. Perhaps this is fairly common.
Thanks for your effort to get such good photos.

Bob