Sentences with phrase «calcites in»

Uranium - series uses the decay of uranium and thorium isotopes (238U, 235U and 232Th) in calcites in particular, such as stalactites and stalagmites in caves.

The primary source of the calcite in limestone is most commonly marine organisms.

Garnets align to host a globes of blue - green calcite in this original earring design.

Mesmerizing in its allure, sleek black onyx meets speckled calcite in this design.

Rain falling on this material dissolved some of the calcite skeletal fragments and then precipitated this calcite in between other grains to cement all of the grains together and turn the material into a limestone.

«Continuous 500,000 - Year Climate Record from Vein Calcite in Devils Hole, Nevada.»

Rainfall from cyclones contains relatively little heavy oxygen so analysing the oxygen isotope ratio of calcite in stalagmites can reveal the extent of cyclone activity.

The calcite in calcium carbonate allows coccoliths to scatter more light than they absorb.

Not exact matches

Pure calcite crystals shatter easily, but the oyster shell is organised in thin layers that shift orientation when stressed, confining damage to shallow craters and stopping fractures spreading (Nature Materials, DOI: 10.1038 / nmat3920).

In January independent teams at MIT and the University of Birmingham showed how to use calcite (a common crystal) to make paperclip - size objects disappear.

A patina of calcite coated the fragment, and the researchers used radioactive uranium in the mineral to date the bone to about 55,000 years old.

Both gypsum and calcite, found in drywall and cement, irritate mucus membranes, like those in the eyes, nose and throat.

The water contains a smattering of uranium atoms that decay into a distinctive isotope of thorium, which accumulates in the calcite over millennia.

And then there are the colored shells from Cueva de los Aviones, a sea cave in southern Spain, where Hoffmann's uranium - thorium dating of a calcite crust covering the objects has just yielded an age of more than 115,000 years.

Aubert cut samples of the cave popcorn, shaving the calcite into ultrathin layers in a process he calls micro-excavating.

Then one day in 2011, a Griffith University archaeologist named Adam Brumm noticed that some of the artwork was covered with calcite growths colloquially known as cave popcorn.

In both cases, the researchers carved out a hiding place in a crystal of the mineral calcitIn both cases, the researchers carved out a hiding place in a crystal of the mineral calcitin a crystal of the mineral calcite.

They remove carbon dioxide from the atmosphere — producing oxygen through photosynthesis and, in another process, forming the calcite plates that Huxley found so interesting.

WAXS (wide angle x-ray scattering) analysis of the crystalline particles finally formed at ambient conditions shows that pure calcite (the stable polymorph of calcium carbonate) forms at pH - values corresponding to high binding strength in clusters and that predominantly vaterite (the least stable polymorph) and traces of calcite form at pH - values corresponding to low binding strength in clusters (fig.

Minerals like calcite grow and dissolve in response to changes in the water composition, which can be characterized by its level of acidity (i.e., the pH).

«Microbes involved in the nitrogen cycle, which are still active today, could have played a major role in calcite precipitation because of their ability to increase the pH,» explains Dr Stinnesbeck.

Through extensive modeling of stratospheric chemistry, the team found that calcite, a constituent of limestone, could counter ozone loss by neutralizing emissions - borne acids in the atmosphere, while also reflecting light and cooling the planet.

In this case, the microscope not only identified signatures corresponding to calcium carbonate as forming the crust, but was also able to differentiate between the calcite and vaterite forms when it was present as a mixture while still attached to the leaf surface.»

He then used the concentration of naturally occurring but unstable uranium in the calcite to estimate how much time had passed since the popcorn formed, giving him a minimum age for the art.

Chen's coworker Baile Zhang of Nanyang Technological University in Singapore, as well as John Pendry at Imperial College London, and their coworkers have shown that a compromise of partial visible - light cloaking of macroscopic objects can be attained using blocks of transparent materials such as calcite crystal, in which light propagates at different speeds in different directions.

Over the next 2 years, Aubert used a diamond saw blade to collect 19 samples of calcite popcorn from 14 paintings in seven caves within a 1 - kilometer radius.

For example, Aubert and his team took 55 samples of the layers of the calcite popcorn, showing that they formed a sort of ministratigraphic sequence in which the layers closest to the art were oldest and the top layers were the youngest.

See urchin spines and mussel shells are made of calcite, because large quantities of calcium are available in water.

Calcite precipitates out of pressurized fluids that travel through rock near faults during some earthquakes and gets deposited in layers, like rings of a tree.

Better yet, more of it was in the crystalline calcite form, which is more stable — and likely to sequester CO2 over geological time — than amorphous CaCO3.

Williams looked at the radioactive elements uranium and thorium trapped in these calcite crystals, using them as a kind of clock based on the rate at which uranium decays into thorium.

The team also showed that calcite associated with two seismic events in the earthquake cluster indicates very rapid carbon dioxide degassing, which can occur when fluid under high pressure is released — like opening the top of a shaken bottle of soda.

He and the rest of the research team, which includes Warren Sharp from the Berkeley Geochronology Center and Peter Mozley of the New Mexico Institute of Mining and Technology, could measure the age of each «generation» of calcite found in the veins and determine when earthquakes occurred relative to one another.

The researchers hope to get a rough age range for the fossils by dating flowstones — calcite structures formed slowly by dripping water — in adjacent rock layers.

This is a scanning electron microscopy image of a calcite crystal generated in the presence of the sea urchin protein rSpSM50 on a silicon wafer showing organized nanotexturing on exposed surfaces.

When the researchers dunked mineral samples in solutions containing both left - and right - handed versions of the amino acid aspartic acid, they discovered that the different versions preferentially stuck to different facets of the calcite crystals.

The newly deposited calcite matches the orientation of the existing crystals, and organic molecules that harden calcite make it even tougher than the original rock, the scientists report in the April issue of Applied and Environmental Microbiology.

The scientists worked with calcite (CaCO3), which has the same composition as chalk and marble and was one of the most abundant minerals in our planet's earliest days.

So the team dated various calcite deposits in the cave and used the assortment of animal remains to deduce that the human teeth were probably between 80,000 and 120,000 years old.

To find out whether acid rain was indeed the problem, the team focused on one problematic sliding layer in the Jiweishan avalanche: a thin bed of black shale, which contains slippery clay minerals such as talc, in addition to fine organic material and calcite, which helps cement the shale together.

Out of several factors we considered in our model simulation, only one (sulphuric acid) could have made the surface ocean severely corrosive to calcite, but even then the amounts of sulphur required are unfeasibly large.

But the most ancient skeletal fossils are made not of bone, but of calcite — the same material that makes up the rock matrix in which they are embedded.

Researchers had long suspected that organic scaffolds caused calcium carbonate to mineralize and find its most stable form, calcite, by creating low energy surfaces where the ions could easily arrange themselves in rows side - by - side.

All of the common crystal forms, including calcite (found in limestone), aragonite (found in mother - of - pearl), and vaterite (found in gallstones), crystallized from solution, often at the same time.

What the team didn't see in and among the many options, however, was calcite forming from ACC even though researchers widely expect it to happen.

Multiple forms often nucleated in a single experiment — at least one calcite crystal formed on top of an aragonite crystal while vaterite crystals grew nearby.

In one demonstration of the instrument's capabilities, the researchers scanned a 70 - by -70-micron sample of calcite as it was first immersed in deionized water and later exposed to sulfuric aciIn one demonstration of the instrument's capabilities, the researchers scanned a 70 - by -70-micron sample of calcite as it was first immersed in deionized water and later exposed to sulfuric aciin deionized water and later exposed to sulfuric acid.

The team observed the acid eating away at the calcite, expanding existing nanometer - sized pits in the material that quickly merged and led to a layer - by - layer removal of calcite along the material's crystal pattern, over a period of several seconds.

Changes in the carbonate ion concentration in seawater can affect the saturation state (and hence biological availability) of several types of calcium carbonate (e.g., calcite, aragonite, or high - magnesian calcite.

coccoliths: Microscopic structures of varying shape and size that are made of calcite, are secreted by calcareous nannoplankton, and are found in marine deposits from the Triassic period to the Recent.