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Post by vegasjames on Nov 29, 2018 4:41:33 GMT -5
First 4 look like calcite. Do they fizz when a drop of acid is put on them?
5,6 and 7 look like selenite.
No idea on the rest.
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Post by fernwood on Nov 29, 2018 4:50:58 GMT -5
Agree with 5-7. Selenite.
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dreamrocks
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Post by dreamrocks on Nov 29, 2018 8:37:24 GMT -5
Agree with 5-7. Selenite. It seems to be harder then selenite. I have small piece of the normal white stuff you find at the gem shows. The color is leaning forwards yellowish green or tannish green. Been looking at for awhile now it does give me the idea may make good cats eyes stones one side has really nice flash. Another club member thought same thing nobody at the club could agree on what the top two are. Thanks for input
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dreamrocks
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Post by dreamrocks on Nov 29, 2018 8:41:49 GMT -5
First 4 look like calcite. Do they fizz when a drop of acid is put on them? 5,6 and 7 look like selenite. No idea on the rest. This is harder then calcite did the test scratch test with calcite. Calcite lost this stuff dug it up but calcite done nothing to It. Thanks for input
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Post by fernwood on Nov 29, 2018 9:07:59 GMT -5
Selenite dissolves in water. The white stuff at rock shows as often Feldspar. True Selenite is the same color as what you posted. I have to thank the RTH experts for that info. Had purchased something from a reputable dealer who said some towers were Selenite. They were white. Actually Feldspar.
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Post by fernwood on Nov 29, 2018 9:11:59 GMT -5
Here is a Selenite specimen I have with positive ID. How does it compare to what you have?
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fuss
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Post by fuss on Nov 29, 2018 10:03:39 GMT -5
looks like orthoclase.
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dreamrocks
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Post by dreamrocks on Nov 29, 2018 10:56:46 GMT -5
Here is a Selenite specimen I have with positive ID. How does it compare to what you have?
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dreamrocks
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Post by dreamrocks on Nov 29, 2018 10:59:45 GMT -5
Except for the what looks like iron oxide identical. Nice thank you. Still going to make at least one cab from it might be interesting cab
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Post by Deleted on Nov 29, 2018 14:22:48 GMT -5
My first thoughts were selenite, gypsum spar, ulexite or similar evaporite. If it is mohs 5-6, then I agree with fuss that moonstone is another possibility. The pink in the last 2 photos looks as if it contains pyrite or moonstone inclusions - also possible in feldspars.
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Post by Deleted on Nov 29, 2018 15:05:10 GMT -5
Since I saw fernwoods post I had to look them up actually does look like many of the ones you talk about to. However selenite and gypsum in all my books are the same thing there is also a gypsum rock that is listed and does say other impurities mixing in the gypsum rock does not list hardness. Gypsum, selenite all lised at 2-2 1/2 this does not scratch at all with a knife the gypsum does. My thought is if gypsum what else is mixed with it that makes it so hard feldspar? I looked in old gemology book I have listed (1st. selenita Spanish for moonstone- feldspar) (2. Selenite colorless gypsum occuring in crystals or large cleavage masses. Used as an ornamental stone especially in Russia. (3. Selenites ( obsolete) Moonstone. Dictionary of gems and gemology 6th edition 1971. I was referring to orthoclase moonstone (the traditional variety, not the labradorite moonstone of recent years), which is one of the feldspars. Though selenite was named after the moon, and gypsum spar sounds like feldspar, they aren't related at all. Selenite, ulexite and similar evaporites are very soft, as is calcite. Feldspars (including moonstone) have a Mohs hardness around 6 (slightly more or slightly less). So, if a knife does not scratch it, moonstone or another of the feldspars is a possibility.
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Post by vegasjames on Nov 29, 2018 19:56:00 GMT -5
First 4 look like calcite. Do they fizz when a drop of acid is put on them? 5,6 and 7 look like selenite. No idea on the rest. This is harder then calcite did the test scratch test with calcite. Calcite lost this stuff dug it up but calcite done nothing to It. Thanks for input I would try the acid test on the first pieces. You cannot always rely on hardness alone as impurities can alter hardness. For example opal is generally considered silicon dioxide, which is softer than aluminum oxide. But aluminum oxide is common in opal and the higher the aluminum oxide content the harder the opal.
5-7 still look like selenite. It has the same sheared face look of selenite. Selenite grows as plates. If you look carefully at the edges of selenite you will see lines where the plates form. When they shear the face will have a very straight relatively smooth look from where the plate separates. So check the edge of the piece and see if you can see the lines from the plate formation.
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Post by vegasjames on Nov 29, 2018 20:00:33 GMT -5
Selenite dissolves in water. The white stuff at rock shows as often Feldspar. True Selenite is the same color as what you posted. I have to thank the RTH experts for that info. Had purchased something from a reputable dealer who said some towers were Selenite. They were white. Actually Feldspar. Selenite will dissolve in water but it literally takes years. When I clean my red selenite crystals I often soak them for a month or more to loosen up the mud to clean them. I even boil them to get mud out of the nooks and crannies.
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Post by vegasjames on Nov 29, 2018 20:08:59 GMT -5
My first thoughts were selenite, gypsum spar, ulexite or similar evaporite. If it is mohs 5-6, then I agree with fuss that moonstone is another possibility. The pink in the last 2 photos looks as if it contains pyrite or moonstone inclusions - also possible in feldspars. Since I saw fernwoods post I had to look them up actually does look like many of the ones you talk about to. However selenite and gypsum in all my books are the same thing there is also a gypsum rock that is listed and does say other impurities mixing in the gypsum rock does not list hardness. Gypsum, selenite all lised at 2-2 1/2 this does not scratch at all with a knife the gypsum does. My thought is if gypsum what else is mixed with it that makes it so hard feldspar? I looked in old gemology book I have listed (1st. selenita Spanish for moonstone- feldspar) (2. Selenite colorless gypsum occuring in crystals or large cleavage masses. Used as an ornamental stone especially in Russia. (3. Selenites ( obsolete) Moonstone. Dictionary of gems and gemology 6th edition 1971. Yes, selenite is a gypsum. Here is a write up I did a while back explaining the different forms of gypsum since sat in spar is so often mislabeled as selenite.:
Clearing Up the Confusion About Forms of Gypsum. There seems to be a lot of confusion over the different forms of gypsum, which in particular is leading to the mislabeling of satin spar for selenite. So I figured I would write this to clear up the confusion. I really like gypsum because of its ability to form in so many shapes. I have collected crystals that look like angle wings, diamonds, one that looked like a bunch of little pentagons stacked on each other, some that look like fish skulls, blades, fish tails, swallow tails, hourglasses, crowns, etc., etc. etc. It also comes in different colors. I have been mining red selenite for years and have also found a deposit of golden selenite, and found one piece of green selenite and an interesting piece of gypsum that was root beer colored. Close by here is a humongous deposit of brown gypsum, some of which is as selenite. And occasionally I can find the clear “white” gypsum commonly referred to as “Utah glass”. Sometimes I find the selenite in clusters or as crystals growing off a primary crystal, but most often as single crystals. Sometimes the gypsum will form flower-like shapes or other shapes bound to sand. Or will contain inclusions of mud. Then there are the opaque types of gypsum such as the fibrous satin spar often incorrectly referred to as selenite. Just so much variety. Many stones have the same chemical make up but are not the same thing. For example chert, sugar quartz, chalcedony, jasper, agate, tridymite, coesite and cristobalite are just a few of the various forms of silicon dioxide. This does not mean they are all necessarily the same thing. I won’t get in to the fact that jasper and agate are forms of chalcedony yet can have differences from what it normally called chalcedony since that is not the topic. Point is that stones can have the same basic chemistry but have other differences such as crystal structure that make them different. In the case of gypsum all gypsum is hydrated calcium sulfate, but not all gypsum is selenite. In short if you want to know if your stone is really selenite simply hold it up to a light source. Can you see right through the gypsum like looking through glass? If yes then you have selenite. If no then you DO NOT have selenite. Selenite by definition is the CLEAR version of gypsum. So let’s look at the definition of some of the forms of gypsum: -Selenite: A clear version of gypsum that looks like glass and you can see right through it. Selenite may have inclusions in it, usually as inclusions of mud. Light still readily passes through the clear areas though. -Satin spar: A fibrous, translucent form of gypsum often used to make sculptures, towers, healing wands, palm stones, etc. If held up to the light you cannot see through it due to the fibrous nature. Very commonly mislabeled as selenite, which again is the clear version of gypsum. Alabaster: A form of massive gypsum for which there is no cleavage seen. May be opaque or can occur in clear crystals. Anhydrite: Technically no longer gypsum since anhydrite is calcium sulfate that is not hydrated. It can be produced by heating gypsum sufficiently to drive off the water. If water is added to anhydrite it converts back in to gypsum. Example of selenite: www.mindat.org/photo-138399.htmlExample of satin spar: www.mindat.org/photo-149274.htmlExample of alabaster gypsum: www.mindat.org/photo-213826.htmlExample of anhydrite: www.mindat.org/photo-288483.html
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Post by vegasjames on Nov 29, 2018 20:10:17 GMT -5
The last one does. Right color and crystal formation.
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