What mineral made these square marks?

Not to be a downer but, In all reality the correct way to label these is Quartz epimorph after "?". Until the original mineral is found in place there are any number of cubic minerals which could have been present and then dissolved away without leaving any indication of what they were.



Edited 1 time(s). Last edit at 11/05/2009 10:06PM by Karl Volkman.

Paul:
Having lived in Presscott and collected at the Copper Basin open pit, I believe your quartz specimens have casts after pyrite.

I'm with Ray and some others on their assessments of the specimen being casts of quartz around long-gone pyrite. Skull Valley is a copper/gold deposit play that has been explored by several mining companies, including Phelps Dodge, now known as FMI. A number of us older geologists have tramped the area and these casts are after pyrite. I remember finding simple unstriated limonite after pyrite cubes in the area. I can dig deeper in my files, but this is my recollection. I haven't visited the area since the 1970s.

Ray, you probably remember all the pyrite veining going on in the creek bed there.

Tony, your knowledge of the Copper Basin area needs to be explored. Can you share some. I have questions about my malachite covered quartz crystals we found. They have a very distinct "desert varnish" rust colour. If you wash them, they come out very clear and undamaged. This pic enclosed had a pinpointed backlight on the tip, maybe not the correct way to photograph, but it adds drama to the image.