mineralia:

Zoisite var. Tanzanite from Tanzania

by Dan Weinrich

mineralia:

Fluorite from Illinois

by Exceptional Minerals

crownedrose:

Did you guys know rubies and sapphires - which are usually seen in jewellery - are actually the same thing?

When I say the ‘same thing’, I mean they are both varieties of the mineral corundum, which forms mainly in metamorphic rocks, but not limited to. They have the same chemical formula, Al₂O₃, yet come in different colours and are known to the general public as different ‘stones’.

Rubies and sapphires both must have a certain amount of colourisation and hues to be considered a specific kind of that gemstone. Sapphires can also come in other colours than the dark blue most people know.

The reasons for all these different colours and hues is dependant on the amount of elements found within the mineral.

For example, the ruby’s pink-to-red colours are because of the presence of the element chromium.

Sapphires come in a more array of colours - blue, purple, green, yellow, pink, etc - due to different elements being present like copper, iron, and magnesium; just to name a few.

The best part is, these are all impurities. Funny how impurities actually make something even more beautiful, right? As well, we all know the diamond is the hardest gemstone, coming in with a 10.0 on the Mohs scale, but rubies and sapphires come very close with a 9.0.

Oh yeah, and these varieties can be fluorescent too. Just a bonus to add to the pure awesome that is corundum. Next time you see these gemstones set in jewellery, you’ll now know some new facts to tell others!

Photo credit goes to:

• Sapphire ring: gemteck1 on Flickr
• Ruby ring: paparutzi on Flickr
• Corundum (var. sapphire): Orbital Joe on Flickr
• Corundum (var. ruby): Orbital Joe on Flickr

(via geologise)

geologise:

Cumulonimbus Cloud Over Africa (NASA, International Space Station Science, 02/05/08) by NASA’s Marshall Space Flight Center on Flickr

“Cumulonimbus Cloud over Africa is featured in this image photographed by an Expedition 16 crewmember on the International Space Station. Deemed by many meteorologists as one of the most impressive of cloud formations, cumulonimbus (from the Latin for “puffy” and “dark”) clouds form due to vigorous convection of warm and moist unstable air. Surface air warmed by the Sun-heated ground surface rises, and if sufficient atmospheric moisture is present, water droplets will condense as the air mass encounters cooler air at higher altitudes. The air mass itself also expands and cools as it rises due to decreasing atmospheric pressure, a process known as adiabatic cooling. This type of convection is common in tropical latitudes year-round and during the summer season at higher latitudes. As water in the rising air mass condenses and changes from a gaseous to a liquid state, it releases energy to its surroundings, further heating the surrounding air and leading to more convection and rising of the cloud mass to higher altitudes. This leads to the characteristic vertical “towers” associated with cumulonimbus clouds, an excellent example of which is visible in this image (right). If enough moisture is present to condense and continue heating the cloud mass through several convective cycles, a tower can rise to altitudes of approximately 10 kilometers at high latitudes to 20 kilometers in the tropics — before encountering a region of the atmosphere known as the tropopause. The tropopause is characterized by a strong temperature inversion where the atmosphere is dryer and no longer cools with altitude. This halts further vertical motion of the cloud mass, and causes flattening and spreading of the cloud tops into an anvil-shaped cloud as illustrated by this oblique photograph. The view direction is at an angle from the vertical, rather than straight “down” towards the Earth’s surface. The image, photographed while the International Space Station was passing over western Africa near the Senegal-Mali border, shows a fully-formed anvil cloud with numerous smaller cumulonimbus towers rising near it. The high energetics of these storm systems typically make them hazardous due to associated heavy precipitation, lightning, high wind speeds and possible tornadoes.”

Image Credit: NASA
Full Caption: http://spaceflight.nasa.gov

mineralia:

Opal from Oregon 

scinerds:

(by tina negus)

The Marston Marble above consists of a whole lot of Promicroceras, an extinct ammonite genus from the Early Jurassic. Their shells are evolute, and are decorated by strong and simple straight ribs that flatten over the venter (belly). These ammonites are more commonly found in the United Kingdom.

(via geologise)

mineralia:

Dioptase with Calcite from Namibia

mineralia:

Quartz with Spessartine & Orthoclase from China

mineralia:

Elbaite from Afghanistan

mineralia:

Brochantite from Mexico

mineralia:

Adamite and Calcite from Mexico

mineralia:

Pyrargyrite from Mexico

mineralia:

Silver from Peru

mineralia:

Emerald from Colombia 

mineralia:

Amazonite with Smoky Quartz and Albite from Colorado