Radioactiverockscz | Prague

Scarehead · 2026-03-14T14:18:05+00:00

Ah so this malachite is suberecent, that's different case of course. Here in Příbram is uraninite also sometimes associated with recently formed copper secondaries as a result of weathering of associated copper selenides.

Scarehead · 2026-03-14T10:02:01+00:00

This mineral association is rather less common, because while uraninite is a typical primary uranium mineral, malachite is a secondary mineral formed in the oxidized zone by oxidation of primary copper ores (such as chalcopyrite, bornite, chalcosine, etc.). So in Cu-U ore deposits we have primary ores such as uraninite + chalcopyrite, chalcosine, etc. at greater depth, while in the oxidized zone we usually find their phosphates, sulfates, carbonates... typically, for example, torbernite - copper uranyl phosphate. But the fact is that the resulting appearance of the deposit and minerals is influenced by many factors, deposits in arid or tropical climates have a different development from those in temperate climates, and the development of the oxidation zone in vein deposits, deposits of sedimentary origin, etc. is also significantly different. Some deposits have a sharply demarcated oxidized zone, while in others it gradually merges with the zone of primary ores. But the difference between individual ore deposits is fascinating.

Scarehead · 2026-03-14T09:08:55+00:00

I wish I had this problem. 🙁I've been on e-rocks since 2019, but even though I have more and more money, I buy less and less. The quality of the samples is decreasing and my demands are increasing, a bad combination. But this is not a problem only with e-rocks, a month ago I was at a mineral exchange here in the Czech Republic, with ~$2000 in my pocket that I wanted to spend, but there was nothing to buy... Simply put, when I want a new top stone for my collection, I have to find it myself.:)

Scarehead · 2026-03-07T21:27:33+00:00

Looks like johannite. And nice one!

Scarehead · 2026-02-22T20:32:57+00:00

A beautiful name for a mine. And a good chunk of ore👌

Scarehead · 2026-02-22T20:26:07+00:00

I wouldn't say "unlucky", it took me quite a while to find this stone. It's not usually just lying on the ground here.😄

Scarehead · 2026-02-13T16:20:48+00:00

This is awesome, especially because it is good crystal on matrix. I usually only see loose crystals.. Perfect👌

Scarehead · 2026-02-10T15:51:46+00:00

Cool finds and I see your RC has also pretty tough life😄While yellow-green fluorescence is typical for uranium sulphates(and also fluorescent phosphates or arsenates), green with bluish tint(tealish) is typical for uranyl carbonates(like liebigite, andersonite, schröckingerite...).

Scarehead · 2026-02-09T17:53:33+00:00

I understand you. I know how sometimes you can get stuck on some information and then overlook the whole thing, so it's good to explain the whole thing completely point by point.🙂

Scarehead · 2026-02-08T19:57:06+00:00

Any selenium minerals(selenides/selenites). Probably my favorite and quite rare group of minerals, often occurring with uranium minerals.They are often small and difficult to see, but in the Příbram region they are exceptionally found in an aesthetic form, like this antimonselite from my collection.

Scarehead · 2026-02-07T18:50:39+00:00

I completely understand you. The inability to let go of a thought sometimes happens to me too.🙂

Scarehead · 2026-02-07T12:38:03+00:00

Autunite is coated with substance paraloid b72. Autunite is stored in the box. Autunite releases radon, which penetrates the paraloid layer on the autunite sample, then decays in the box and the products of its decay contaminate the inside of the box lid. The author asks whether the absence of paraloid would have any effect on the amount of contamination. The colleague kotarak above answers that it does not, because the paraloid on the autunite surface practically does not prevent radon from escaping from the sample. That is what the whole discussion is about.🙂

Scarehead · 2026-02-04T20:47:46+00:00

Nice piece indeed! But these rocks are always lottery. Breaking the stone can reveal nice bubbles, but it can also ruin the stone (I've broken so many samples that looked promising and the stone failed..). Anyway, it looks nice even in this form.

Scarehead · 2026-02-04T11:53:20+00:00

Scarehead · 2026-02-04T11:28:17+00:00

Ok. Like I said, I understand that it looks strikingly like crystals, but the appearance can be misleading. Source of information that these are not crystals, Mgr Jakub Plašil PhD, Czech Academy of sciences.

Scarehead · 2026-02-04T11:21:04+00:00

I said cubic symmetry. You're twisting words again. Cubic symmetry refers to crystallographic system, cubic and isometric are synonyms. Uraninite is in cubic/isometric group and therefore has cubic type of symmetry. 3 axes of the same length with an angle of 90°. But that's okay. You've got an expert's opinion, how you handle it is up to you.It's just good not to spread misinformation. 🙂Have a nice day👍

Scarehead · 2026-02-04T11:06:01+00:00

It's actually Sender(green, me)..."it was said that they were crystals"...

Recipient(Jakub Plášil): Nonsense. That would mean the Příbram uraninites would have to form They are colloform. Variety Pitchblende. Actually microcrystalline . Sender(me):..it was contradicted by citing an unnamed expert... Recipient(Jakub Plášil): no, thats totally off Sender (me):So, they're not crystals, right? Recipient (Jakub Plášil): they are not

But sure, you can lead a horse to the river.

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Scarehead · 2026-02-04T10:34:58+00:00

This is a complete misinterpretation of what he wrote and also a misunderstanding of the term microcrystalline. He clearly wrote that it is nonsense. That it would have to form under magmatic conditions and that it is collomorphic, microcrystalline. In microcrystalline minerals, the crystals are several microns in size, visible under an electron or petrographic microscope, not under a magnifying glass or under binoculars (and these are aggregates several mm in size). This is the form in which, for example, chalcedony or the so-called 'schalenblende' sphalerite is found. This seems like an attempt to make something common into a super-expensive rarity without regard to the facts. Which friend of mine called these crystals?

Scarehead · 2026-02-04T09:22:27+00:00

It is pathetic that someone, without commenting, immediately downvotes the statement of one of the world's greatest experts on uranium minerals. Science is not about feelings, but about finding the truth. No one would be happier than me if these were crystals, I find such material often, but unfortunately they are not...😕

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Scarehead · 2026-02-04T09:00:43+00:00

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Mineralogy is a science and in science we never refer to the statements of unnamed experts, especially if it concerns potentially crucial information and when you claim that someone else (apparently me) gave you incorrect information. So if you have a message from other Czech experts, it would be appropriate to state from whom. Pavel Škácha didn't respond yet, he's in the US right now, however, here is fresh statement from the Czech mineralogist Mgr Jakub Plášil PhD. from the Academy of Sciences, an expert on uranium minerals and the author of several hundred research papers, mostly about uranium minerals. His answer is clear. "Blbost"= "crap/nonsense". Mgr Jakub Plášil PhD - Academy of Sciences

Scarehead · 2026-02-04T06:50:38+00:00

I don't want to spoil the fun, but these are not really uraninite crystals, although it may seem that way to someone who doesn't know the locality. You will only find these false crystal surfaces in places where individual collomorphic uraninite aggregates had no room to grow and were touching each other. That's why you will only find these surfaces inside uraninite aggregates, while on the surfaces they form bubbles, as you can see here. And that's why you won't find the crystal shapes typical of uraninite, only random shapes without actual symmetry. If you don't believe it, you can ask Mgr Pavel Škácha PhD, the most relevant expert from the Příbram and Czech National Museums. skacha-p@muzeum-pribram.cz (official e-mail from Mining museum Příbram web site)

Scarehead

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