geopop

Iridescent Native Silver

Something about the structure in which the metal precipitated from the element charged fluid that carried and concentrated the silver from its source rock is acting like a diffraction grating, much like the regular arrangements of silica spheres in opals. The spacing in the structure is similar in size to the wavelengths of visible light, and the light diffracts into its component wavelengths. In this specimen from Norway (4.1x4.4x3.5cm) the bright shiny silver shimmers across a spectrum of red, green and blue, while dull grey silver sulphides such as acanthite and polybasite sit next to it atop the matrix.

Loz

Smog Envelops Beijing: Before and After Pictures as City Goes on Red Alert

Reed Flute Cave

As Christmas bears down on us, you may have undergone the effort of decorating your home with fairy lights that flash bright and colourful. The image below reminds me much of that, but it is no way a house or a Christmas decoration. This is the inside of a cave in the Guangxi province of China whose delicate and unusual stalagmite and stalactites have astonished tourists for centuries.