Al Kidwell was a well known exploration geologist and mineral collector active primarily in the south central US. I interacted with him briefly some decades ago. He discovered his namesake mineral, a sodium iron phosphate, at various phosphate mines and localities in Arkansas, this one is from Shady. The yellow is the iron phosphate mineral cacoxenite, the pale green-yellow is the kidwellite, and the red-brown and black are both goethite.
Image is a PS photomerge of four stacks of from 200 to 320 images each, taken with a Mitutoyo 10X objective, reverse Raynox 150, Canon 50D, and WeMacro rail with 5 micron steps. Aside from the merge, PS only for minor contrast and brightness, cropping and resizing. ZS DMap with Pmax corrections. I am quite pleased how well the photomerge worked on this. Full size image is here : https://www.mindat.org/photo-1158855.html
Kidwellite and friends
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Kidwellite and friends
It's not what you look at that matters, it's what you see - Henry David Thoreau