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Post by johnw on Sept 6, 2018 22:04:37 GMT -5
radial (hemi-spherical) crystallization of the agate makes the domes. This happens with both primate agate bands, and when as a psuedomorph over an existing crystal of another mineral. Banding is often much smaller scale layer of radial hemi-spheres on top of the layer of domes. the basic answer is close together radial spheres or hemi-spheres, and then layers of new agate bands across the Botryoidal surface. This occurs in many minerals. From wikipedia: "Botryoidal minerals form when many nearby nuclei, specks of sand, dust, or other particles, are present. Acicular or fibrous crystals grow radially around the nuclei at the same rate, appearing as spheres. Eventually, these spheres abut or overlap with those that are nearby. These nearby spheres are then fused together to form the botryoidal cluster." Thank you debt123redux for your explanation. So the question becomes over the span of millions of years during the formation process, how can the yellow coloration be confined just to one area and form the "yolk" as it were? The seepage of minerals is prevalent, but yellow seems an odd happening. One more question, where can I find out how crazy lace is mined in the limestone tufts in Chihuahua? Any good reading on this? Cheers, johnw  I have read with interest what has been said and looked at this piece from different directions and this is what I came up with, several pictures of which clearly show what caused the "egg" (hem-spherical) crystallization formation over some other material, for which I need know the name, particularly the red,, pink and brown projections forming from the base. Certainly the comment of 'eggs" being formed one layer at a time is proven out, but I don't know how the layers formed with so much chaos going on in and around the structure itself.  Here is the original piece showing the result of all the chaos involved during its evolution.  Closer views showing the layering.  Here is the back of the piece, showing the origins of the layers forming the "eggs"   One layer at a time. What is the red projection at the base of the "Botryoidal formation"? 
What is the name of the pink and brown minerals forming the "base" projection?
  Final images. Cheers, johnw |
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Post by johnw on Sept 10, 2018 1:50:42 GMT -5
One layer at a time, up close and personal. Interesting formation prior to botryoidal formations occurring. Cheers, johnw  |
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Post by johnw on Sept 10, 2018 10:55:14 GMT -5
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