Sentences with phrase «many calcite»

Several types of minerals — especially ultrapure crystals of calcite, cordierite, and tourmaline — can split a beam of sunlight to form two images, with polarized light taking a slightly different path than the main beam.

This is best shown with the eyes, where even the single calcite crystal lenses survived intact.

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).

A mix of red mineral stone and calcite balance the pH of the purified water and reincorporate minerals like magnesium and potassium that are good for your body and can actually improve the taste of your water.

But as you descend underground, past Titania's Veil (a gleaming white calcite formation), crossing Giant's Hall and skirting the mirror surface of Dream Lake, you will hear an ethereal music start to fill the dripping hush.

The adapted cultures produced even more new biomass and about twice as many calcite platelets than the control group under the high temperatures.

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.

Therefore, the researchers analysed the ratio of the inorganic calcite platelets to the organic carbon inside the cells after the adaptation phase.

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

Grind a few flecks of calcite off a cave painting, measure the ratio of uranium and thorium isotopes, and you can read out the age of the calcite.

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.

«The challenge is to find these calcites.

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 calcite.

«Crinoids and other echinoderms have a skeleton comprised of innumerable individual calcite plates held together by various connective soft tissues.

The real magic is an optical property of calcite called anisotropy.

By using powerful photon beams generated by the Advanced Photon Source (APS), a DOE User Facility located at Argonne, researchers have shown that they can now control the chemical environment and provide nanoscale structural detail while simultaneously imaging the mineral calcite as it is pushed to its extremes.

To see what happens to the calcite when it is destabilized, researchers used a technique called X-ray reflection interface microscopy (XRIM) at the APS.

As the X-rays pushed the calcite to more extreme levels of instability, researchers were surprised to see that the dissolving pits became distorted and formed ink splatter - like irregularities, indicating that some parts were dissolving quicker than others.

Piercing through water solution and reflecting off the calcite's surface like a mirror, focused X-rays changed the water's acidity level, starting a chain of reactions that lowered the pH and caused the calcite to dissolve.

Also given are the solubilities of vaterite, aragonite, and calcite (27)(SOM section 2.5.)

The specific forms of each coccolith most likely evolved under pressure from zooplankton, the microscopic animal group a notch up the food chain that developed mandibles, claws, and other accoutrements for getting past the hard calcite coccoliths.

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

Only later would scientists learn that coccoliths are calcite plates that surround some species of phytoplankton like armor.

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.

«Calcite is well - studied,» said Fenter, «and so we have a very good understanding of how it grows and dissolves over a wide range of conditions.

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).

Sea urchins have seemingly countless spines each made from a single calcite crystal.

«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.

Unlike typical crystal structures like shells, which incorporate thousands of smaller, geometrically symmetrical crystals attached to each other, each spine on a sea urchin is a single large calcite crystal with its own convoluted shape.

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.

At the foot of a massive speleothem, or mineral deposit, they found the remains of two young men, their skeletons dismembered and encrusted with calcite.

They suspect that vaterite may be present on more plant species, but that the unstable mineral is being converted to calcite when exposed to wind and rain.

So why do these species produce a calcium carbonate crystal crust and why are some crusts calcite and others vaterite?

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.»

This may also be the reason why some plants have both vaterite and calcite present at the same time.

The sea urchin spines are mostly made of calcite, usually a very brittle and fragile material.

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.

The thin calcite deposits on cave art can be contaminated by new flows of uranium - containing water, dust, or other detritus, making the art seem older than it is, he and his colleagues argued.

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.

But they conclude that marine organisms with skeletons made of high - magnesium calcite may be especially susceptible to ocean acidification because this form of calcium carbonate dissolves more easily than others.

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

It gives the crystal calcite its famous ability to produce double images of objects.

As they form over time, stalagmites develop annual layers of the mineral calcite, which are broadly similar to the rings of a tree.

This would also explain the unusual lack of typical pond fossils at the site, as well as the near lack of gnaw marks on bones and calcite and barite concretions found on bones excavated from the quarry.