Tuff Schist

The adventures of an unstable geologist

145 notes

bunnybundy:

April 12, 1981 - after a two day launch delay, the world’s first Space Shuttle, Columbia, launches from the Cape. STS-1’s crew, John Young and Bob Crippen, become the ultimate test pilots, flying NASA’s first manned maiden flight of any spacecraft. Unaware of a potentially catastrophic fire in the front wheel well, Young lands Columbia perfectly on April 14, after 37 orbits of the Earth. He becomes the only human being to fly the Gemini, Apollo and Shuttle crafts, and to have walked on the moon.

(via circuitdesign)

6 notes

earth-coordinates:

Say hello to the extinct Exogyra texana! These little guys lived during the Cretaceous and helped form reef complexes. Most are found in central Texas and I found my specimens in a road cut in Llano.

earth-coordinates:

Say hello to the extinct Exogyra texana! These little guys lived during the Cretaceous and helped form reef complexes. Most are found in central Texas and I found my specimens in a road cut in Llano.

235 notes

distant-traveller:

Io in true color

The strangest moon in the Solar System is bright yellow. This picture, an attempt to show how Io would appear in the “true colors” perceptible to the average human eye, was taken in 1999 July by the Galileo spacecraft that orbited Jupiter from 1995 to 2003. Io’s colors derive from sulfur and molten silicate rock. The unusual surface of Io is kept very young by its system of active volcanoes. The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter’s other Galilean moons. The resulting friction greatly heats Io’s interior, causing molten rock to explode through the surface. Io’s volcanoes are so active that they are effectively turning the whole moon inside out. Some of Io’s volcanic lava is so hot it glows in the dark.

Image credit: Galileo Project, JPL, NASA

distant-traveller:

Io in true color

The strangest moon in the Solar System is bright yellow. This picture, an attempt to show how Io would appear in the “true colors” perceptible to the average human eye, was taken in 1999 July by the Galileo spacecraft that orbited Jupiter from 1995 to 2003. Io’s colors derive from sulfur and molten silicate rock. The unusual surface of Io is kept very young by its system of active volcanoes. The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter’s other Galilean moons. The resulting friction greatly heats Io’s interior, causing molten rock to explode through the surface. Io’s volcanoes are so active that they are effectively turning the whole moon inside out. Some of Io’s volcanic lava is so hot it glows in the dark.

Image credit: Galileo Project, JPL, NASA

(Source: apod.nasa.gov, via circuitdesign)

18 notes

mineralogue:

Calcium Carbonate Concretions: Ooids, Oolite, and Pearls
Image: surface of an ooidic limestone from Gunlock, Utah. From wikimedia commons, in the public domain.
Ooids are spheroidal grains less than 2mm in diameter displaying growth banding around a central nucleus or “seed”. They usually form in warm, shallow marine water, where the agitation of waves allows accretion around the nucleus on all sides. Warm water helps enhance the precipitation of calcium carbonate, which is the primary component of most ooids, usually in the form of aragonite. Larger grains formed similarly are known as pisoids. Ooids may also be composed of phosphate, chert, dolomite, or iron minerals such as hematite or goethite.
Oolite is a sedimentary rock formed from ooids, spherical grains, cemented together. Oolitic limestone is composed of calcite or aragonite ooids with calcite acting as the cement.
Aragonite ooids may sometimes resemble pearls, which are also calcium carbonate (either aragonite or a mixture of aragonite and calcite) deposited concentrically around a central “seed”. Ooids are not iridescent, but then neither are most pearls: almost all shelled molluscs are capable of forming pearls, but only those produced by specific oysters and mussels are the perfectly round, iridescent, gem-quality concretions that is most commonly associated with the word “pearl”.

mineralogue:

Calcium Carbonate Concretions: Ooids, Oolite, and Pearls

Image: surface of an ooidic limestone from Gunlock, Utah. From wikimedia commons, in the public domain.

Ooids are spheroidal grains less than 2mm in diameter displaying growth banding around a central nucleus or “seed”. They usually form in warm, shallow marine water, where the agitation of waves allows accretion around the nucleus on all sides. Warm water helps enhance the precipitation of calcium carbonate, which is the primary component of most ooids, usually in the form of aragonite. Larger grains formed similarly are known as pisoids. Ooids may also be composed of phosphate, chert, dolomite, or iron minerals such as hematite or goethite.

Oolite is a sedimentary rock formed from ooids, spherical grains, cemented together. Oolitic limestone is composed of calcite or aragonite ooids with calcite acting as the cement.

Aragonite ooids may sometimes resemble pearls, which are also calcium carbonate (either aragonite or a mixture of aragonite and calcite) deposited concentrically around a central “seed”. Ooids are not iridescent, but then neither are most pearls: almost all shelled molluscs are capable of forming pearls, but only those produced by specific oysters and mussels are the perfectly round, iridescent, gem-quality concretions that is most commonly associated with the word “pearl”.