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Search found 41 matches |
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Jim Robison Replies: 31 Views: 48260 |
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An important clue is the difference in shape between the two minerals. Fluorite is aa cubic mineral, which among other things mean the corners of natural crystals have a square shape or a variation on ... | |
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Jim Robison Replies: 528 Views: 6285105 |
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Kevin
I am a self described 'carbonate freak', focusing from 1988 to 2000 on all carbonates, and thereafter smithsonite and dolomite from Tsumeb exclusively. This is a great area of collection foc ... |
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Jim Robison Replies: 158 Views: 304789 |
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Thanks John
Do you know of other instances where the quartz/cristobalite associations occur? I'd be interested to know, in general, the environments these these two minerals, and trydimite, occur in ... |
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Jim Robison Replies: 158 Views: 304789 |
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A large group of amethyst from Rio Grande do Sul, Brazil, with inclusions of cristobalite.
John, I don't know the silicates at all well, but have long been under the impression that cristabolite and ... |
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Jim Robison Replies: 6 Views: 11064 |
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A mineral has a specific chemical formula and composition. While concrete is an aggregate of several types of rocks and processed lime, with water, it is rock like in character. Generally speaking, a ... | |
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Jim Robison Replies: 19 Views: 29937 |
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As an Ex Arizona resident who drove through Quartzite many times on the way to and from Los Angeles I saw Quartzite all through the year. Only stopped there to get gas and something to eat. Quarzite h ... | |
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Jim Robison Replies: 24 Views: 45105 |
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For years I was unfocused (I thought) until a symposium where the theme was carbonates. By the time I had pulled stuff from my case and flats, about 70% of the collection was on the table. So I decide ... | |
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Jim Robison Replies: 8 Views: 28385 |
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Peter and others, thanks for sharing memories of one of the truly great people I have known. I too knew it was coming, and the pleasure of your recollections captures the man perfectly. I got to know ... | |
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Jim Robison Replies: 12 Views: 26144 |
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Hi Heimo, far from ugly:-) A whole little mountain full of pockets.
Helmo I agree with Pierre . Ugly is in the eye of the beholder. I used to belong to an organization that at it's annual we ... |
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Jim Robison Replies: 9 Views: 20463 |
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Cesar,
Many of us probably did not comment because our knowledge of such topics is either very incomplete or (in my case) non-existent!!! I have always valued your contributions to FMF. and not bein ... |
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Jim Robison Replies: 18 Views: 34388 |
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Regarding the habit of smithsonite noted above. This is a classic Tsumeb habit. I have a friend with a specimen holding crystals over 10cm long. Stunning piece. In my large Tsumeb smithsonite collecti ... | |
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Jim Robison Replies: 2 Views: 15644 |
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I want to update my password, but can't figure out where in the site to do this. I suspect it is someplace really obvious, but sure don't see it. Help please! | |
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Jim Robison Replies: 2616 Views: 2770257 |
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Mike
A simple scratch test with a steel needle in an out of the way place on the clear crystals would give a good indicator on the quartz versus smithsonite question. I've been reminded by a goo ... |
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Jim Robison Replies: 2616 Views: 2770257 |
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Mike Your excellent new pics have a puzzle or two in them. On the second shot, with the layered material it seems most likely you are looking at dolomite. The first pic has an anomaly in that the ... | |
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Jim Robison Replies: 2616 Views: 2770257 |
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AM
Your latest Tsumeb smithsonite is beyond lovely. Very nice indeed. The yellow bleb inclusions are commonly attributed to either cadmium or greenockite (cadmium sulfide). Unfortunately, there is ... |
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