FyeahGeology

somme: Honeycomb weathering, photographed by Justin Friend

Wed, 22 May 2013 03:26:13 +0100

Honeycomb weathering, photographed by Justin Friend

From National Geographic Space Pictures This Week; May 17,...

Wed, 22 May 2013 02:59:56 +0100

From National Geographic Space Pictures This Week; May 17, 2013:

Sea of Sand ESA

A dry riverbed (seen in light blue) cuts across the Namib desert (map) in Namibia, in a picture released by the European Space Agency on May 10.

Taken by the Korean satellite Kompsat-2, the white “waves” in the image that appear to be breaking along the red sand dunes are actually salt deposits.

rhamphotheca: pleoros: Ófærufoss, Iceland (photo: Thierry...

Wed, 22 May 2013 02:48:39 +0100

rhamphotheca:

pleoros: Ófærufoss, Iceland

(photo: Thierry Hennet)

definitelydope: Torfajökulssvæði (by Sverrir Thorolfsson)

Tue, 21 May 2013 06:52:28 +0100

definitelydope:

Torfajökulssvæði (by Sverrir Thorolfsson)

scinerds: Moqui Marbles and Martian Blueberries The photo...

Tue, 21 May 2013 03:26:26 +0100

scinerds:

Moqui Marbles and Martian Blueberries

The photo above shows Moqui Marbles in their native habitat of southern Utah. These curious rocks are actually concretions having iron (hematite) rinds.

Very similar rocks, called blueberries, have been observed repeatedly on Mars by the rovers. Click here to see an image taken by the Opportunity rover of the blueberries. Some scientific papers implicate the possibility of life on Mars playing a role in their formation while others do not.

Discussions about the pros and cons of their formation have been quite lively at times. However, the consensus seems to be that both the marbles and the blueberries were created beneath the surface as naturally occurring substances, most likely minerals, precipitated from flowing groundwater. Pictured with the marbles is a Devil’s-Claw cactus (Sclerocactus parviflorus). — Bret Webster

themineralogist: Azurite with Malachite from Mexico

Mon, 20 May 2013 22:59:16 +0100

themineralogist:

Azurite with Malachite from Mexico

beautiful-avalanche: Mount Ol Doinyo Lengai [Tanzania] by...

Sat, 18 May 2013 13:37:16 +0100

beautiful-avalanche:

Mount Ol Doinyo Lengai [Tanzania] by Olivier Grunewald

abluegirl: Marble Cathedral, Chile, Photograph by Karl-Heinz...

Fri, 17 May 2013 06:52:07 +0100

abluegirl:

Marble Cathedral, Chile, Photograph by Karl-Heinz Raach
A series of caves and tunnels formed from marble is at the center of Chile’s Lake General Carrera. The Patagonian lake crosses the border into Argentina, where it’s called Lake Buenos Aires.(x)

amoanimus: Tropfsteinhöhle Cave, Austria.

Fri, 17 May 2013 03:26:07 +0100

amoanimus:

Tropfsteinhöhle Cave, Austria.

malformalady: A tongue of lava oozes out from beneath the...

Fri, 17 May 2013 02:06:51 +0100

malformalady:

A tongue of lava oozes out from beneath the recently cooled crust of a flow. The silica contained within, reflects the early morning sunlight, giving its surface a glassy sheen.

Photo and caption credit: Bruce Omori

woodendreams: (by Aubrey Stoll)

Thu, 16 May 2013 10:17:46 +0100

woodendreams:

(by Aubrey Stoll)

geologicaltravels: 2013: Vertically dipping sandstones outside...

Thu, 16 May 2013 09:45:10 +0100

geologicaltravels:

2013: Vertically dipping sandstones outside Tamarite de Litera, Spain.

colchrishadfield: Canada rocks.

Thu, 16 May 2013 03:26:21 +0100

colchrishadfield:

Canada rocks.

fuckyeahmineralogy: Vanadinite on baryte; Morocco

Wed, 15 May 2013 22:27:54 +0100

fuckyeahmineralogy:

Vanadinite on baryte; Morocco

fuckyeahmineralogy: Shattuckite; Democratic Republic of Congo

Tue, 14 May 2013 23:07:26 +0100

fuckyeahmineralogy:

Shattuckite; Democratic Republic of Congo

geologyboy: Skarns These are metasomatic deposits characterised...

Tue, 14 May 2013 17:08:54 +0100

geologyboy:

Skarns

These are metasomatic deposits characterised by calc-silicate minerals e.g. garnet, amphibole, diopside, and wollastonite.

They are often irregular masses, and occur close to or at intrusion margins. They commonly replace existing lithologies e.g. limestones, carbonate-cemented shales.

Exo- vs endo-skarns: Endoskarns replace intrusion rocks, and exoskarns replace country rocks.

They can be a source of a variety of ores which are targeted for the following elements: Fe, Cu, W, Zn, Pb, Mo, Sn, U. They are also mined for industrial minerals (aka the boring ones).

(sorry for using symbols for elements, but build a bridge).

Formation:

Initial isochemical metamorphism of the country-rock by intrusions, followed by multiple stages of metasomatism caused by magmatic and/or hydrothermal fluids, whose temperatures range from 400-800 centigrade. Minerals are precipitated due to decreasing temperatures of transporting fluid and reaction with country-rocks.

On top of this you can have retrograde alteration and destruction of early skarn minerals by infiltrating meteoric fluids.

themineralogist: Ruby (red) in Cordierite under ultraviolet (by...

Tue, 14 May 2013 13:43:27 +0100

themineralogist:

Ruby (red) in Cordierite under ultraviolet (by someHerrings)

mineralists: Spherocobaltite and Dolomite Musonoi Mine, Congo

Tue, 14 May 2013 10:17:29 +0100

mineralists:

Spherocobaltite and Dolomite
Musonoi Mine, Congo

mineralists: Cavansite on StilbiteWagholi, India

Tue, 14 May 2013 09:43:27 +0100

mineralists:

Cavansite on Stilbite
Wagholi, India

Some facets of the Geology of Diamonds | Metageologist

Mon, 13 May 2013 06:24:35 +0100

Some facets of the Geology of Diamonds | Metageologist:

all-geo:

The ‘Picasso diamond’ shows complex growth patterns highlighted by cathodoluminescence. Image with permission of University of Edinburgh