Petrified Wood

Petrified Wood

I bought Carol a bag of rough rocks to use as gifts to our grandchildren who gladly accept them.  She must have forgotten and I stumbled across it a couple weeks ago.

I was waiting for a microscope objective to arrive and decided to try the process at which I am not good to identify them.  The bag included color pictures  of the 25 possibilities.  How hard can that be?  The process was more involved than I originally thought. I started with the one above which turned out to be petrified wood.

Petrified Wood

I began by photographing it with differing compositions.   After the first day I still had no idea.

Petrified Wood

 Wood is "petrified" when minerals replace its cells.

The thing that got me going was on the second day, I remembered I had seen vendors at the rock and mineral show displaying their samples with a water bath which made them appear more beautiful and tried it.  I soaked the sample and looked it over with a hand lens.  The realization suddenly dawned on me.

Petrified Wood

The knowledge of its identity, opened up my possibilities for photographing it.  I finally knew where I was going.

Petrified Wood

Petrified Wood

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Cross Polarization in Extreme Photomicrography

Chalcotrichite

This sample is from Ray Mine, Pinal Co., Arizona.  The chemical formula is Cu2o.  It shares the same formula with Curprite.

The reason my pictures of minerals seem to come slowly is because they do.  I'm learning as I go.  The minerals with the formula Cu2O have been an extreme challeng for me.  Without any accomodations the images turn out with the highlights blown.  I've tried several things to keep them from looking like the one below.

Chalcotrichite with blown highlights

The one at the top of this page is about the best I've been able produce.   Here is how I do it.

I place all of my minerals in a FotoDiox Portable Studio, LED 440 to photograph them.  I have incorporated Cross Polarization in this way.

FotoDiox Set up

I have made two filters to mount in the studio between the light and the subject.  The top one is what I call a softbox filter made of white nylon mounted on a frame.  The one underneith is linear polarizing film mounted on a frame.  I add a circular polarizing filter on the lens as shown below.

Circular Polarizing Filter

I can then twist the circular polarizing filter to minimize the highlights.  I also underexpose at least 1 stop. Adobe Bridge has a setting which controls highlights and I minimize that.

Clar Led Light 24B 

The multiple polarizing filters cause a many stops loss of light so some times I add  the above ligyht before closing the lid to augment the light.  In the image at the top of this page I didn't add the Clar Light but I augmented the ISO to 800.

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