Sentences with phrase «of calcite»

The brittle star Ophiocoma wendtii and its relatives are decorated with a surface layer of calcite hemispheres.

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.

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

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.

Using the X-ray Reflection Interfacial Microscope powered by the Advanced Photon Source, researchers can both watch and drive the nanoscale changes of the surface of a calcite mineral as it dissolves in real - time.

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.

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.

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.

In this image, researchers observe distortions in the reaction front (the boundary between the blue and red regions) as they form on the surface of the calcite mineral, driven by the high solution acidity where the reaction fronts become unstable.

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 acid.

The climate records of calcite shells show that yesterday's Arctic — as in during the Ice Age — had warm water.

Luckily, the conditions in the flowstone - cave lead to the accumulation of several thin layers of calcite on the inner and outer surface of the skull fragment.

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.

S. scardica secretions are composed of calcite and vaterite.

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 real magic is an optical property of calcite called anisotropy.

These veins of calcite reveal a record of fluid - driven earthquakes clustered together on a fault typically characterized by less frequent, periodic earthquakes caused by mechanical stress.

The bacteria enhanced the formation of calcite even when they were just lying around, not growing or multiplying.

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.

Around the egg is a membrane, and evenly spaced on the membrane are points where columns of calcite (a form of calcium carbonate) form.

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

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.

«We see two possible reasons for this: Either the algae exchanged the high - magnesium calcite against a less soluble composition or they lost part of the calcite due to acidification.

The aquatic blue - green hues of calcite encircle the wrist in this beaded bracelet from Thailand.

Designed and crafted by Tiraphan Hasub, the bracelet is completed with petite brass beads that alternate with the beads of calcite.

At malapa, berger had gotten lucky datnig the sediba bones lay between site - uri de dating gratuite din elvetia flowstones - thin layers of calcite deposited by running water - that could also be dated radiometrically.

«When methane is released from the seafloor, a different type of calcite encrusts those left - over foraminifera shells.

Marine organisms that build their shells out of calcite, in contrast, might not begin dissolving until the end of the century.12

«The surface temperature and pressure on Venus coincide approximately with the P - T equilibrium of the calcite - wollastonite mineral reaction, and atmospheric sulfur species are probably involved in rapid heterogeneous reactions with the surface.

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

This is also true for minimum binding strength (pH = 9.75), at which traces of calcite are still obtained.

Coralline algae usually build their cell walls from a form of calcite that contains a high amount of magnesium.

Crystals of calcite, like this one, may have been the «sunstones» of Viking legend that enabled these seafarers to successfully navigate lengthy voyages.

But in the early 2000s, scientists devised an alternative dating strategy based on the thin layer of calcite that can form when groundwater seeps down a cave wall and across a painting.

Each color highlights a continuous single - crystal of calcite (CaCO3) made by the sea urchin Arbacia punctulata, at the forming end of one of its teeth.

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.

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.

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.

It typically consists of aragonite, made of calcium carbonate in a crystalline form that differs from that of calcite.

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.

Hey, why not invent a form of calcite - shell - forming plankton that would build floating cities instead?