Uranium from Příbram (Czechia)

All images are links to high quality versions. RC-102: 1.7 kCPS [43 uSv/h]. AB+: 55 CPS, 1960 CPS

Uraninite nodules in calcite (?). Unlike the Colorado plateau rocks, the veins are nice and clean (although not chemically pure) which results in a shiny surface.

RC-102: 1.1 kCPS [37 uSv/h]

Chunk of Uraninite growing on calcite.

It has nice botryoidal formations of massive Uraninite along with some areas where the shape of the underlying calcite crystal is visible. A few of the "bubbles" are broken, showing the individual crystals that grew on the matrix.

RC-102: 300 kCPS [14 uSv/h]. AB+: 25 CPS, 704 CPS

Ugly Uraninite chip.

Might glue this inside a cloud chamber or something: it's small, crumbly and weathered.

RC-102: 3.2 kCPS [112 uSv/h]

Uraninite coating "granite".

RC-102: 1.3 kCPS [32 uSv/h]. AB+: 26 CPS, 1200 CPS

Granite with Uraninite veins running through it. A nice crystal of calcite is visible in the third photo.

Uraninite veins running through calcite (?). This might look cool if cut and polished.

RC-102: 732 CPS [15 uSv/h]. AB+: 1.75 CPS, 240 CPS

This piece has a (somewhat metamorphic) sedimentary host rock, which is very different from the other pieces.

Geology notes:

The deposit sits on the boundary between quartz-monzonite and pelite. (hence the two different host rocks) The sedimentary rock is from the upper Proterozoic, while the uranium crystallized ~260 million years ago (from U-Pb dating). The igneous intrusion are roughly 100 million years older than the uraninite.

The presence of calcite suggests a hydrothermal process where the uranium was leached out the surrounding rock by calcium bicarbonate and reprecipitated as CO2 escaped from the solution. The resulting "vein deposit" occupies pre-existing gaps in the rock.

Because the deposit is fully underground, all my samples were mine tailing and I have very little context.

Also, for political reasons, It'll be a few years before I can get these home. Don't expect better photos or more measurements for a while

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