Mi(ni)Geo

Sulphur Crystals on Matrix (by cobalt123)

Sulphur Crystals on Matrix - A superb specimen of yellow sulphur crystals, well-formed and distinct on a matrix with white calcite crystals. This was shot through the glass display case at the Tucson Rock and Gem Show 2012.

Silver and copper (by FEI Company)

Silver particles and perfect copper crystals. Courtesy of Wadah Mahmoud.

Gold, fine cubo-octahedral crystals on goethite. (via Hunterian Museum Geology Collections)

Gold ore (Callion/Australia). Native gold in association with colloform goethite indicates contemporaneous precipitation. Width of micro-photo corresponds to approx. 250 microns. (via Geneva Ore Deposits Group)

Calcita. Encuadre 2 cm. Col. Gonzalo García (Fot. Honorio Cócera). (via MTI Blog)

Opal rough, cameo and doubler. (via GeoScenic)

Calcosina. 8 mm. Col. Gonzalo García (Fot. Honorio Cócera). (via MTI Blog)

Haematite and Calcite (by Hypocentre)

Haematite sample, with some pink stained calcite crystals. From Florence Mine in Cumbria.

(Source: eximago)

Dolomite Veins (by ColetteSimonds)

Palos verdes peninsula - forrestal reserve.

Mineral specimen of onyx agate amygdale. Dunure Railway, Brown Carrick Hills, Ayrshire. The specimen consists of chalcedony in the form of parallel-banded onyx and concentrically-banded agate. The different colours of white, greys and pinks represent different layers laid down at different times by percolating fluids. (via GeoScenic)

Diamagnetic Levitation 2 - Bismuth (by PaulsLab)

The first shot shows the setup of this experiment. One big cylindrical magnet, made from neodymium (NdFeB), is hung at the top, above two plates of bismuth. Bismuth is element nr. 83; a highly diamagnetic metal. Diamagnetic means that it creates an opposing magnetic field if there is a magnetic field close to it. That means that it will repel a magnet. The small cube between the two plates of bismuth is also made of neodymium (NdFeB) and measures 5x5x5 mm. The two plates of bismuth repel the magnet, but they are not strong enough to overcome gravity. This is solved by the big cylindrical magnet on top of it all attracting the small magnet. If all elements are aligned carefully, the small magnet will float stably between the two bismuth plates. You can easily push the magnet and it will go back to the center. It can spin for hours!

(Source: kentaur)

One doesn’t normally think of talc as a rock, not if they grew up with talcum powder. But a rock it is, and sometimes forms lovely little patterns like this. It’s also interesting, being a metamorphic mineral. This is what happens to serpentinite and related rocks when carbon dioxide and water are present. (via En Tequila Es Verdad)

Bismuth Crystal (by Paul’s Lab)

This is a synthetic bismuth crystal. It measures 4x3x2,5 cm and was made by myself, Paul, from www.paulslab.com.