What might the minerals in these rock speimens be?

[M.E.G.]

These were found at an elevation of 3800ft, thereabouts. Small Out cropping. There is told of Cinnabar and Uranium discovered years back in this general area. Not known for volcanic venting discoveries as far as my reseach has come up with at this time. Although, the one speimen looks to be pumis, it is MUCH heavyer than any pumis of the same size I have held.

 

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[rodoconnor]

Some of those look to have some cinnabar. Post in the rocks and gem forum, they'll nail it

 

[Bejay]

I'll offer an attempt.

All looks to come from an igneous extrusional source. Sometimes the material can be highly gaseous, and yet other times far less. Highly mineralized extrusions often occur...depending on the "alphabit soup"....or the makeup of the molten material. While extrusional sources can be varied, they often occur from fissures as opposed to noted volcanic monuments. I might suggest looking on the Land Matters Structural Geology Maps that show the area in which the specimens were found. Structural mapping often offers detailed explanations.

Very interesting samples, and worthy of diagnostic tests......or assay! I believe you have enough info to explore some possibilities. But likely someone familiar with those types of specimens in southern Oregon can offer a more conclusive 1st hand opinion. I have often taken samples to a State Geologists Office or even a major Oregon University Geology Dept for an opinion.

Bejay

 

[DDancer]

I would not worry about uranium as its a very disbursed mineral in its ore bodies. Definitely looks like cinnabar and metacinnabar for the red and metallic samples. The first picture with the butterscotch stone appears to be jasper with metacinnabar. Interesting stuff Its safe enough in its current form... just don't heat it *or do it very carefully if you want to verify the presence of mercury*... just wash you hands after handling it.

 

[gold tramp]

my eyes arent the best and its hard to tell without touching for me, jasper is what it appears to be. it has what appears to be conchoidal type of fracture to it ?
GT.....................

 

[Bejay]

As a side bar:
Rocks are originally formed under specific igneous geologic characteristics. Yet they can be altered to become altered into other forms of rocks such as metamorphic or sedimentary. (3 basic types of rocks: Igneous, metamorphic, & sedimentary). Often there is even a mix of the various forms......especially along intrusions/extrusions adjacent to preexisting rock formations. The possibilities are endless. Upon looking at the jasper like rock (concoidal fracturing/cleavage) one can still see a color characteristic that is seen in the other rocks. if all the rocks came from the same local, then it would appear that some alteration occurred along the transitional line of the formation; and yet possibly there were some formation events occurring at different geologic times.

If we tend to think that a single intrusion/extrusion occurred we often find that such occurrences happened many different times in geologic history and the geologic conditions changed.

For an example that might be easily understood: Lets take a volcano. It can have many different eruptions over a long geologic period of time. Each eruption can be different. When Mt St Helens blew the last time it took with it much of the existing volcanic cone.....the resulting soup, if you will, had a different characteristic than say another eruption. One thing is for sure in Geology: "Things Change".

Bejay

Not attempting to preach to the choir, but for some less knowledgable, such understanding is often overlooked.

 

[DDancer]

Gold tramp yes the fracturing is of the type you are thinking of. That type of fracturing is common to high silicate materials. In conjunction with the cinnabar and the properties apparent in the other samples a strong hydrothermal deposit with possible tendency toward volcanic origin but not volcanic in nature. My thoughts which mirror Bejay's first post.