Sierra Colorada (Argentina, L5)
I formerly cut a Sierra Colorada (Argentina, L5) and two of the slices obtained contained large (almost centimetric) vugs, some making the 3 mm thick slice hollow! Looking inside is again really breathtaking. Several 5 to almost 10 mm (!) euhedral metallic crystals (also pyritohedral in shape) can be seen, aligned or dispersed, some as quasi isolated single crystals, onto the vug walls. One of them is sectioned through cutting and that small cut face (clearly seen on 2 pictures) indicated to me, from the typical luster of the cut section, that these could be schreibersite (also possible, though perhaps less likely than troilite). See pictures 4741 and 4744.
This is as spectacular as looking into a geode of a terrestrial mineral (although I have never seen terrestrial schreibersite, if ever it exists, because phosphides should readily yield phosphates in contact with air).
My friend Roger Warin, not only expert in taking spectacular pictures of thin sections, was also able to realize superb close-ups of these geodes and "schreibersite" crystals.
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