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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: 403649" data-attributes="member: 4386"><p>It is difficult to find good descriptions. However generalized geological descriptions that I possess mention marble, and skarn (a rock formed by reaction of fluids evolved from things like granite when it intrudes the marble). Also ultramafic rocks, which are always high in chromium.</p><p></p><p>Yes, all sorts of things can be made to look good in the right hands, but I don't much like black opaque stones myself - personal preference,. No flashes of colour and refraction, no banding or colour variation. However things like jet were quite popular in the 19th century (also black powder when ground). Yes, black spinel will take any amount of wear and tear - quite hard (one less than corundum in Moh's scale). Another fairly common stone (in appropriate mineral fields) is black diamond, which can look good as a cluster rim of tiny black around a large white diamond. Anything can look good with the right imagination and skill.</p><p></p><p>I didn't mention, but even some of the coloured spinels are slightly magnetic.</p><p></p><p>Also it depends on marketing - making people think something looks good so they will buy it. Champagne diamonds as from the Kimberleys used to be a colour so far down the list for diamonds that no one wanted them - until a good marketing exercise was put in place. White was always preferred over all else. However I was once taken in to the strongroom in the Premier mine in Pretoria (SA), surrounded by armed guards, and among the beautiful stones I saw were huge diamonds of every colour under the sun. At the time they said buyers did not much want them, but imagine vivid blues, reds and yellows in large transparent stones with the refractive index of diamond! I also saw the ore coming over the grease plates and diamonds clustering there like gravel - an amazing sight.</p></blockquote><p></p>
[QUOTE="user 4386, post: 403649, member: 4386"] It is difficult to find good descriptions. However generalized geological descriptions that I possess mention marble, and skarn (a rock formed by reaction of fluids evolved from things like granite when it intrudes the marble). Also ultramafic rocks, which are always high in chromium. Yes, all sorts of things can be made to look good in the right hands, but I don't much like black opaque stones myself - personal preference,. No flashes of colour and refraction, no banding or colour variation. However things like jet were quite popular in the 19th century (also black powder when ground). Yes, black spinel will take any amount of wear and tear - quite hard (one less than corundum in Moh's scale). Another fairly common stone (in appropriate mineral fields) is black diamond, which can look good as a cluster rim of tiny black around a large white diamond. Anything can look good with the right imagination and skill. I didn't mention, but even some of the coloured spinels are slightly magnetic. Also it depends on marketing - making people think something looks good so they will buy it. Champagne diamonds as from the Kimberleys used to be a colour so far down the list for diamonds that no one wanted them - until a good marketing exercise was put in place. White was always preferred over all else. However I was once taken in to the strongroom in the Premier mine in Pretoria (SA), surrounded by armed guards, and among the beautiful stones I saw were huge diamonds of every colour under the sun. At the time they said buyers did not much want them, but imagine vivid blues, reds and yellows in large transparent stones with the refractive index of diamond! I also saw the ore coming over the grease plates and diamonds clustering there like gravel - an amazing sight. [/QUOTE]
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Gemstones, Minerals & Fossils
Gemstones and Minerals
❓Your Mineral Identification Questions answered here
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