Tag: geology

earthstory:

Vanadinite

These beautiful orange crystals are the main source of Vanadium and a minor source of lead, being a lead-vanadium chloride within the apatite group (see https://www.facebook.com/TheEarthStory/posts/1081644598563250:0). They are rare, only forming when lead ore deposits such as galena are oxidised, usually in arid climates, as circulating fluids alter the original rocks forming secondary minerals. The vanadium is leached from the wall rocks, and mixed with the lead before precipitation. Crystallising in the hexagonal system, they usually have a six sided shape. It is both brittle and dense, and only has a hardness of 4 (same as a copper coin) on the Mohs scale. It gradually darkens on exposure to light, so specimens should be kept in a dark cabinet.

Colour ranges from red through orange to brown Morocco is the best source for spectacular mineral specimens like this one, but it also occurs in Europe (Austria, Spain, Scotland), Africa (South Africa, Namibia) and the Americas (USA, Argentina). Discovered in Mexico in 1801, and originally named brown lead, their analysis led to the discovery of the element Vanadium. The mineral has also been known as Johnsonite.

Loz

Image credit: Rob Lavinsky/iRocks.com

http://webmineral.com/data/Vanadinite.shtml
http://www.mindat.org/min-4139.html
http://www.minerals.net/mineral/vanadinite.aspx
http://www.galleries.com/Vanadinite

Source: facebook.com

downtowncamera:

On this day in 1985, the Nevado del Ruiz volcano near Armero, Colombia erupted. The eruption caused lahars to occur, causing the deaths of nearly 25 000 people. If you’re unfamiliar with the term lahar, the brief rundown is they are essentially volcanic mudflows. In this instance the eruption melted the ice caps on the mountain causing the massive lahars to travel through a combined 14 villages at a rate of six meters per second, destroying utterly everything in their path. It was during this event that 13 year old Omayra Sanchez was trapped up to her neck in concrete, mud and debris. When rescuers found her they discovered that her legs were trapped and she could not be extracted from her pit. Omayra spent the remaining 60 hours of her life trapped waiting for pumps to arrive so that a rescue attempt could occur. During the course of the rescue efforts, photographer Frank Fournier took the photograph above, ultimately winning the World Press Photo award for the year 1986. The photograph has since gone on to become renowned for Omayra’s haunting expression and her state of despair, and is considered one of the most moving pictures taken. Omayra Sanchez died on November 16, 1985.

apostalism:

Yellowstone erupts like clockwork with a periodicity of approximately 600,000 years – in case you were curious, it last erupted 630,000 years ago. The initial blast would probably instantly kill everyone and everything from about Salt Lake City, Utah to Billings, Montana and Salmon, Idaho to Casper, Wyoming (the purple), though everything between San Francisco and Chicago would basically be unlivable due to ash fall, and ash would rain as far away as Mexico and southern Florida.

The ash would be pretty devastating for the United States The fallout would include short-term destruction of Midwest agriculture, and rivers and streams would be clogged by gray muck. On top of that, global cooling would wreak havoc on global agriculture for more than a decade likely spawning famine and severe winters.

camelotsqween:

ANCIENT HISTORY MEME – 1/10 Events in the Ancient World

“Ashes were already falling, not as yet very thickly. I looked round: a dense black cloud was coming up behind us, spreading over the earth like a flood.’Let us leave the road while we can still see,’I said,’or we shall be knocked down and trampled underfoot in the dark by the crowd behind.’We had scarcely sat down to rest when darkness fell, not the dark of a moonless or cloudy night, but as if the lamp had been put out in a closed room.”

           ~ Pliny the Younger, eye-witness account of the Destruction of                       Pompeii addressed in a letter to Tacitus.

noordinarysunset:

Excavated ruins from the ancient city of Pompeii, buried in meters of ash and volcanic rock after the eruption of Mt Vesuvius in 79 AD (background). An estimated 10,000 people were killed, wiping out the entire city in one catastrophic swoop. Pompei was lost for more than 1500 years, lying undiscovered until 1599. Because of the lack of exposure to air and moisture, their bodies were found in the exact positions in which they died, some of them fetal and others of them clamoring for safety. But also in these ruins is clear evidence of an active, thriving 1st century Roman town, complete with an amphitheater, a temple, baths, a forum, gymnasium and a complex water system. The site is elaborate and astonishingly well-preserved.


Pompeii, Italy