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Gemstones, Minerals & Fossils
Gemstones and Minerals
❓Your Mineral Identification Questions answered here
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<blockquote data-quote="user 4386" data-source="post: 485010" data-attributes="member: 4386"><p>Yes it is possible although I have not seen an example involving tourmaline. It is also possible for a basalt to be altered at a later time by boron-rich fluids when a granite intrudes nearby (but this would cause other mineralogical changes in the basalt itself). Hence my question re the unit name. I know people don't like giving localities, but in many cases a broad locality would be helpful, and a rush on some of these things as a result is unlikely (pretty, interesting, but often not particularly valuable). Minerals such as you mention (and zircon, sapphire etc) are quite common inclusions in basalt. Some are formed from the magmas, others incorporated along the way (xenocrysts - "stranger" crystals, if composite lumps they become xenoliths = "stranger" rocks). In Victoria we have basalts with xenoliths of mantle material, and vein quartz, and granite and even limestone altered to other minerals. I don't discount such possibilities in this case, but they seem large and abundant.</p></blockquote><p></p>
[QUOTE="user 4386, post: 485010, member: 4386"] Yes it is possible although I have not seen an example involving tourmaline. It is also possible for a basalt to be altered at a later time by boron-rich fluids when a granite intrudes nearby (but this would cause other mineralogical changes in the basalt itself). Hence my question re the unit name. I know people don't like giving localities, but in many cases a broad locality would be helpful, and a rush on some of these things as a result is unlikely (pretty, interesting, but often not particularly valuable). Minerals such as you mention (and zircon, sapphire etc) are quite common inclusions in basalt. Some are formed from the magmas, others incorporated along the way (xenocrysts - "stranger" crystals, if composite lumps they become xenoliths = "stranger" rocks). In Victoria we have basalts with xenoliths of mantle material, and vein quartz, and granite and even limestone altered to other minerals. I don't discount such possibilities in this case, but they seem large and abundant. [/QUOTE]
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Gemstones, Minerals & Fossils
Gemstones and Minerals
❓Your Mineral Identification Questions answered here
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