Macro Photography IV and Geology

Subject

I set out in this session to produce and image which showed detail throughout.  This was captured with the Sigma 105 mm macro lens on a Sigma 2x converter with a canon 500d closeup lens mounted up front.  It gives a 2.6x on the sensor image.

Sigma 105mm lens on a Sigma 2x converter with a Canon 500d mounted

This arrangement is much better balanced and the movements generated by the focus rail are small enough.  

Machinist's Scale at 2.6X

While producing the image at the top I could not help wondering what I was photographing.  It is a "rock" I laid out for photographing.  The tiny inclusions are in my opinion definitely metal of some kind.  Initially I was thinking quartz for the bedding and that would mean that the metal was either gold or copper.  The metal seemed corroded so I decided that it was copper.  As a last check before writing about it, I decided to check the hardness.  It cleaved under the pressure of the standards stones.  I eventually determined that it was soft, 3 to 4 on the mohs scale.  I checked its reactivity with acid and it was an effervescing one.  That leads me to believe it is Calcium Carbonate or something like it.  I am now completely unsure about the metallic inclusions.  I am almost completely sure they are metal.  Help!  The bedding has perfect cleavage.  I think I can see cleavage lines in the shot at the top.  It does not taste salty.  It is soft.  It reacts with acid.

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