The Earth Story

Triboluminescence; Sugar Coated.

Imagine you are traveling with the ancient Native American Ute shamans in the American Midwest, hunting for quartz crystals. After collecting the crystals and placing them into ceremonial rattles made of translucent buffalo skin, you wait for the night-time rituals to begin to summon the spirits of the dead. When it is dark, you shake the rattles and they blaze with flashes of light as the crystals collide with one another.

What is the cause of this ‘spiritualistic’ dance of light? Well, you are experiencing one of the oldest known applications of triboluminescence, a physical process through which the light is generated when materials are crushed, rubbed, and ripped—as electrical charges are separated and reunited. The resultant electrical discharge ionizes the nearby air, triggering flashes of light.

In 1620, the English scholar Francis Bacon published the first known documentation of the phenomena, in which he mentions that sugar will sparkle when “broken or scrapped” in the dark. This was also taught to me in my first chemistry lecture at University, it's an easy experiment to carry out at home by breaking sugar crystals in a dark room. Another experiment can be carried out with WintOgreen Lifesavers candy, the wintergreen oil (methyl salicylate) in the candy absorbs ultraviolet light produced by the crushing of sugar and reemits it as blue light.

The spectrum of light produced by sugar triboluminescence is the same as that for lightning. In both cases, electrical energy excites nitrogen molecules in the air and they're ready to party. Most of the light emitted by nitrogen in the air is in the ultraviolet range that our eyes cannot see, and only a small fraction is emitted in the visible range. When the sugar crystals are stressed (aggravated not agitated), positive and negative charges accumulate, finally causing electrons to jump across a crystal fracture and excite electrons in the nitrogen molecules.

Here is something else that’s cool: If you peel Scotch tape in the dark, you may also be able to see emitted light from triboluminescence. I haven’t tried this so guys, if you do, let me know the outcome! Interestingly, the process of peeling such tape in a vacuum can produce x-rays that are sufficiently strong to create an x-ray image of the finger! Of course, I haven’t tried this and I probably wouldn’t recommend anyone else doing so either.

Take home message: Scratching a sugar cube is sweet.

~ JM

Image Credit: http://bit.ly/1HeKruE

More Info: Triboluminescence short intro: http://bit.ly/1CElHFq

WintOgreen Candy experiment: http://bit.ly/1KI20l0

Triboluminescence with quartz: http://bit.ly/1FwsqIO

Triboluminescence in sticky tape:http://bit.ly/YTKqcG

The most complex mineral

This pretty little yellow mineral has just been named Ewingite, after Stanford professor of Nuclear Security Rodney C. Ewing. It was found in a closed Uranium mine in the Czech Republic – the same mine that provided material for Marie Curie’s experiments. Over the last century, water flowing through the mine reprocessed the now-exposed ore into new material like this little Ewingite. Although this crystal is small, X-ray data shows that in fact, Ewingite is the most complex mineral currently known to occur on Earth.

The next 2 images show the structure of the compound, obtained by scientists at the University of Notre Dame using X-ray techniques. Uranium and calcium atoms sit in a number of sites, with oxygen atoms and carbonate groups surrounding them. The full structure repeats around a large open cage, capable of bonding to OH groups. The full chemical formula of the mineral is Mg8Ca8(UO2)24(CO3)30O4(OH)12(H2O)138.

The mineral has a tetragonal symmetry, meaning there is a 4-fold symmetry axis in the unit cell. A single unit cell, the unit that is repeated to make up the full crystal structure, is a rectangular polyhedron 35.142Å x 35.142Å, x 47.974Å, where the unit cell of something simple like halite (simple table salt) has dimensions 5.6404 Åx 5.6404 Å x5.6404 Å (an Å is a unit of distance useful for things about the size of an atom, it is 10 to the -10 meters).

Apparently X-ray crystallographers categorize the complexity of materials based on how many “Bits of data” are required to record all of the positions in a single unit cell. The previous record holding mineral was paulingite, a zeolite, with 6766.99 bits of data required for one unit cell. Ewingite’s unit cell required 23,000 bits of data to record all of its positions, more than 3x as complex as the previous record holder. This is not shabby even compared to the most complex material humans have ever created - Al55.4Cu5.4Ta39.1, which required 48,538.63 bits of data to characterize its unit cell.

-JBB

Image credits and original paper: http://ntrda.me/2G93YRv http://bit.ly/2k8BDnB https://www.mindat.org/min-1804.html_ _

Plankton shell at the nanoscale

A striking image of a plankton shell by Oscar Branson, a PhD student at Cambridge Earth System Science, University of Cambridge, was shortlisted for the inaugural UK Natural Environment Research Council (NERC) student photography and short article writing competition.

The image was obtained using X-radiography at the Diamond light source, an intense X-ray synchrotron radiation source at Rutherford Appleton Laboratory, Harwell, UK. It shows the intricate detail of the shell structure of this tiny marine organism, called Ammonia tepida. Smaller than a grain of sand, this shell is made by a single-celled organism called a ‘foraminifera’.

Oscar's research is revealing how the chemistry of such fossil shells provides clues about past climate on Earth, going back many millions of years.

The four judges were Jonathan Bates, Director of Communications for NERC; Harriet Jarlett, a science writer for NERC; Dr Helen Czerski an oceanographer and TV presenter on popular science programmes; and Professor Simon Redfern.

Kirsty Grainger, Head of Skills and Careers at NERC said: "We were delighted by the response to this inaugural competition. The diversity in the winning entries alone highlights the breadth of world-class research training NERC PhD funding supports. Congratulations to all the winners and thanks to all the judges and all those who submitted entries; the judges’ task was not an easy one!"

~SATR

CambridgeESS on fb: www.facebook.com/CambridgeESS

See more at: http://www.nerc.ac.uk/press/releases/2013/87-competition.asp_ _

This is a single crystal of olivine erupted from a volcano in Chile in 1932. Scientists have scanned and X-Rayed this tiny grain in high detail and are looking at the 3-D structure of the mineral, including faces and even inclusions of trapped magma stuck inside.

X-ray vision changes ideas about Earth's core

Our planet’s interior is complex and has many layers. Their formation and structure contain many unsolved mysteries. But new research is providing some clues about how Earth’s internal structure may have evolved.

If you were to take a journey to the centre of the Earth you would find most stuff there is made of just three elements, at least until you’re about around 3000 km below the surface. These elements – oxygen, silicon and magnesium (plus a little bit of iron) – make up more than 90% of Earth’s “ceramic” mantle. Electrically and thermally insulating, the minerals of the mantle are the stony part of the planet.

But as you go deeper, things suddenly change. About midway to the centre, you cross a boundary from the stony mantle into the metallic core, initially liquid in its upper stretches, and then solid right in the centre of the Earth. The chemistry changes too, with almost all of the core being composed of iron.

The boundary between the metallic core and rocky mantle is a place of extremes. In physical characteristics, Earth’s metallic liquid outer core is as different to the rocky mantle as the seas are from the ocean floor. One might imagine an inverted world that has storms and currents of flowing red-hot metal in the molten outer core. It is this flow of metal in the core that gives Earth its magnetic field, protects us from the solar storms that constantly bombards us, and has allowed life to thrive.

How did such distinct layers of material end up next to each other? In a paper published in the journal Nature Geoscience, a group of scientists led by Wendy Mao of Stanford University have shown how metallic iron may be squeezed out of rocky silicates at depths of around 1000km beneath the crust.

Experiments on mixtures of silicate minerals and iron cooked up in the lab show that iron sits in tiny isolated lumps within the rock, remaining trapped and pinned at the junctions between the mineral grains. This observation has led to the view that iron only segregates in the early stages of planetary formation, when the upper part of the silicate mantle was fully molten. It is thought that droplets of iron rained down through the upper mantle and pooled at its base, then sank as large “diapirs” driven by gravity. These fell through the deeper solid mantle to eventually form a core.

Mao’s work suggests that this model needs revising. The team used intense X-rays to probe samples held at extreme pressure and temperature squeezed between the tips of diamond crystals. They found that when pressure increases deep into the mantle, iron liquid begins to wet the surfaces of the silicate mineral grains. This means that threads of molten iron can join up and begin to flow in rivulets through the solid mantle, a process called percolation. More importantly, this process can occur even when the mantle is not hot enough to form a magma ocean.

“In order for percolation to be efficient, the molten iron needs to be able to form continuous channels through the solid,” Mao explained. “Scientists had said this theory wasn’t possible, but now we’re saying, under certain conditions that we know exist in the planet, it could happen. So this brings back another possibility for how the core might have formed.”

~SATR

http://www.geopoem.com/2013/10/how-earth-got-her-core.html

Image: A filamentary network of iron may have developed between grains of minerals deep in the Earth, early in its history (Credit: Crystal Shi, from Nature Geoscience DOI: 10.1038/NGEO1956)

Original paper: http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1956.html

OBSCURE OBSIDIAN

Every year or so, I get a phone call to help the local archeologists clean out the drawers where they keep their most difficult finds: these are stones that they believe to be tools, but the stones are in such a condition that they can’t be easily identified. So they call me.

I’m not allowed to scrape them to check for hardness, or pick off a piece for analysis in an XRD, can’t make them into thin sections, can’t drip acid on top of them to see if they fizz – can’t do anything but look at them, usually through a hand lens or stereo microscope. It’s a geologist’s nightmare of having to try to identify little bitty rocks with both arms tied behind my back.

As I examine their little treasures, their eyes light up with hope every time I pause and sigh over one of their small black rocks. They hope, oh how they hope, that I’ll identify a bit of obsidian for them. It would make their year, possibly decade, to find obsidian among their unidentified flakes and pebbles.

Obsidian is often referred to as volcanic glass. It is formed from the rapid cooling of lava, a cooling so fast that mineral crystalline structures are not given time to develop. Instead of getting a stone composed of minerals, one gets a stone comprised of an amorphous lithic blob. Since the constituents of obsidian did not have time to organize into minerals, the composition of obsidian is complex, and the composition of obsidian varies from volcano to volcano, and even can vary between eruptions within a single volcano. Obsidian is rare enough and useful enough as an extremely valuable stone tool (the, ahem, “cutting edge” of stone age technology) that it was passed around and bartered between early societies. Knowing the composition of obsidian is a fingerprint of its source, and knowing this source gives the archeologist the ability to trace its path along ancient trade routes and interchange among our early ancestors – the “IP” address of the stone age!

If a small bit actually does turn out to be obsidian, it could be analyzed but to do this takes months, sometimes years, access to specialized laboratories and even nuclear facilities – not to mention funding to pay for analyses in our economy-challenged world today. Recently a new method for analyzing obsidian was developed – one which can be done in ten seconds in the field or even on little fragments in the archeologists’ drawer. Scientists at the University of Sheffield have managed to design a portable X-ray florescent analyzer that can analyze obsidian on the spot, with precision high enough to determine the volcanic fingerprint of the artifact.

So, I look at the little fragments offered by our archeologists, and however much I wish to please them (they give me coffee and cookies after all), none of the little black bits has the characteristic conchoidal fracture (which looks like the surface of a broken piece of glass) that is the only identifying feature that would allow me to classify it as true and proper obsidian. Alas! But there is always next year and always hope!

Annie R Image is one of our Greek obsidians, showing flow banding that indicated that the lava that formed the obsidian was in motion at the time it “froze.”

http://www.heritagedaily.com/2013/09/new-10-second-sourcing-technology-set-to-transform-archaeology/98939 http://volcano.oregonstate.edu/book/export/html/389http://archaeology.about.com/od/oterms/g/obsidian.htm --And thanks to I F**king Love Archeology for the heads-up on the pXRF!

Watch an X-ray scan of a mastodon skull

New Insights Into the Crab Nebula

Five observatories teamed up to spy on the Crab Nebula and the results are incredible. The VLA (radio) views are shown in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple. The Crab Nebula is the remnant of a bright supernova explosion first spotted by the Chinese in 1054. Located 6,500 light-years from Earth, the Nebula is home to a super-dense neutron star. The stellar powerhouse -- known as a pulsar and seen as a bright dot in the center of the image -- emits pulsing lighthouse-like beams of radio waves and light as it rotates (or pulses) once every 33 milliseconds.

The super-dense star does more that put on a dazzling display of stellar strobe lights, it also gives the nebula it's intricate shape. A fast-moving blast of particles emanating from the pulsar, combines with material ejected by the supernova explosion and its progenitor star, to form the distinctive shape we know as the Crab Nebula.

This incredible new video starts by showing us a composite image of the Crab Nebula, created by combining data from five observatories spanning nearly the entire breadth of the electromagnetic spectrum: the Very Large Array, the Spitzer Space Telescope, the Hubble Space Telescope, the XMM-Newton Observatory, and the Chandra X-ray Observatory.

From the image, the video dissolves to the red-colored radio-light view illustrating how a neutron star’s fierce “wind” of charged particles energizes the nebula, ultimately causing it to emit the radio waves. Next we see the yellow-colored infrared image from Spitzer, which shows the glow of dust particles absorbing ultraviolet and visible light. Then we see through Hubble's eyes as the green-colored visible-light image offers a sharp view of hot filaments that permeate this nebula. Lastly, we see the blue-colored ultraviolet image and the purple-colored X-ray image, which highlight the effect of an energetic cloud of electrons driven by a rapidly rotating neutron star at the center of the nebula.

Image & Source Credit: Credits: NASA, ESA, J. DePasquale (STScI)

https://youtu.be/ZiGuh0yISao

Fifty shades of very dark grey

Mercury is an unusual planet in a number of ways. It is small, dark-surfaced, rich in volatile (reactive) elements, and has a relatively large core.

In around 2011, analysis of information from the MESSENGER spacecraft indicated that Mercury was unusual in another way; the rocks that made up its volcanic plains were depleted in iron compared to similar rocks on Earth, suggesting that its mantle was correspondingly iron-poor. This had implications for the primordial crust that would have formed as the planet cooled from its early ‘magma ocean’ stage; it had to be buoyant enough to float on top of a not terribly dense mantle. In 2015, it was proposed that this ‘primary’ crust may have been composed, implausibly enough, of graphite. However, even if true, after a couple of billion years of meteorite bombardment and volcanic eruptions it was unlikely that anything of the primary crust could still be detected on the surface.

Or so you might think.

For some time, geophysicists had also been puzzled by the dark colour of Mercury's surface. On most rocky planets iron acts as the darkening agent, but MESSENGER showed that Mercury simply doesn’t have enough of it in its crust to colour it significantly. The dark, unreflective material that it does have is particularly concentrated in and around large impact craters, suggesting that it comes from deep below the surface. Recently, X-Ray and Neutron Spectometry has confirmed that this material is most likely graphite, and not only that but its distribution is consistent with thick remnants of the predicted primordial crust persisting below the surface.

If true, this means that Mercury is much richer in carbon than the other terrestrial planets. Why that might be we do not yet know; but it opens the door to the possibility that differences in its original accretionary environment might be able to explain its other oddities. If so, that would also tell us more about the processes at work when our solar system was originally formed.

Photo credit: NASA Sources: http://bit.ly/1W5NL0e http://bit.ly/1R6bsHO http://bit.ly/1YtLnSp

Triboluminescence; Sugar Coated.

Imagine you are traveling with the ancient Native American Ute shamans in the American Midwest, hunting for quartz crystals. After collecting the crystals and placing them into ceremonial rattles made of translucent buffalo skin, you wait for the night-time rituals to begin to summon the spirits of the dead. When it is dark, you shake the rattles and they blaze with flashes of light as the crystals collide with one another.

What is the cause of this ‘spiritualistic’ dance of light? Well, you are experiencing one of the oldest known applications of triboluminescence, a physical process through which the light is generated when materials are crushed, rubbed, and ripped—as electrical charges are separated and reunited. The resultant electrical discharge ionizes the nearby air, triggering flashes of light.

In 1620, the English scholar Francis Bacon published the first known documentation of the phenomena, in which he mentions that sugar will sparkle when “broken or scrapped” in the dark. This was also taught to me in my first chemistry lecture at University, it's an easy experiment to carry out at home by breaking sugar crystals in a dark room. Another experiment can be carried out with WintOgreen Lifesavers candy, the wintergreen oil (methyl salicylate) in the candy absorbs ultraviolet light produced by the crushing of sugar and reemits it as blue light.

The spectrum of light produced by sugar triboluminescence is the same as that for lightning. In both cases, electrical energy excites nitrogen molecules in the air and they're ready to party. Most of the light emitted by nitrogen in the air is in the ultraviolet range that our eyes cannot see, and only a small fraction is emitted in the visible range. When the sugar crystals are stressed (aggravated not agitated), positive and negative charges accumulate, finally causing electrons to jump across a crystal fracture and excite electrons in the nitrogen molecules.

Here is something else that’s cool: If you peel Scotch tape in the dark, you may also be able to see emitted light from triboluminescence. I haven’t tried this so guys, if you do, let me know the outcome! Interestingly, the process of peeling such tape in a vacuum can produce x-rays that are sufficiently strong to create an x-ray image of the finger! Of course, I haven’t tried this and I probably wouldn’t recommend anyone else doing so either.

Take home message: Scratching a sugar cube is sweet.

~ JM

Image Credit: http://bit.ly/1HeKruE

More Info: Triboluminescence short intro: http://bit.ly/1CElHFq

WintOgreen Candy experiment: http://bit.ly/1KI20l0

Triboluminescence with quartz: http://bit.ly/1FwsqIO

Triboluminescence in sticky tape: http://bit.ly/YTKqcG

Really neat science...using X-Ray imaging to read text on papers that were buried in Herculaneum, one of the cities destroyed in the 79 a.d. eruption of Mount Vesuvius

2014: International year of crystallography Originally at the core of mineralogy, it initially explored crystal form and angles, later moving on to examining optical properties in thin sections of rock in varied forms of polarised light, and then to xray diffraction patterns, which revealed the intimate nature of the building blocks of rocks to the geological world. As the 20th century advanced the discipline became equally central to the life (and congruent pharmaceutical) sciences, once researchers realised that many biochemical constituents of life, such as proteins and DNA, are also crystalline. From the examination of the arrangements of atoms in crystal structures and observation of their properties, prediction became possible, in much the same way that Mendeleev intuited many non discovered elements when constructing his periodic table of the elements. This practise is at the root of the modern pharmaceutical industry. This year has been internationally chosen to celebrate this discipline, so next time you gaze at a beautiful crystal, spare a thought for the toiling crystallographers slaving over a hot microscope or xray diffraction apparatus, and raise your beer to them... Loz Image credit of a lush aquamarine crystal with white albite feldspar and grey muscovite mica matrix from Pakistan 7.8 x 3.8 x 3.5 cm : Rob Lavinsky/iRocks.com Loz http://www.iycr2014.org/