Sentences with phrase «calcite forms»

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.

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.

Without the polymer, they saw crystals of vaterite and a little calcite forming randomly under the microscope.

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.

Not exact matches

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.

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.

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.

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.

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.

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

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.

Calcite crystals are also formed such that different facets have mirror - image atomic - scale structures.

They found that the bacterium produces carbonate crystals that form a cement that binds tightly to existing calcite grains, lining the walls of the pores without plugging them.

This tiny all - rounder produces considerable amounts of biomass and calcite — a relatively stable form of calcium carbonate — and releases a climate - cooling gas.

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.

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.

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

The team used a high concentration of calcium carbonate that naturally forms a crystalline mineral known as calcite.

Acidification increases the corrosiveness of the water and is also driving a decline in the amount of carbonate ion, needed to make aragonite and calcite, two forms of calcium carbonate that many marine organisms use to build their shells and skeletons.

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.

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

A star - burst of lapis lazuli petals forms an ethereal chrysanthemum centered with blue calcite and green and blue quartz.

The salt that forms on the surface of concrete (efflorescence) is often a combination of calcium sulphate (gypsum), salt (sodium chloride) and calcium carbonate (calcite).

The limestone consists of similar skeletal fragments that have been cemented together with calcite to form a rock.

The answer is the calcium carbonate in the form of calcite found in coral, limestone, marble, and other mineral deposits.

Present - day ocean surface waters are supersaturated for the major carbonate mineral forms used by marine organisms, including the more soluble form aragonite (corals, many mollusks) and the less soluble form calcite (coccolithophores, foraminifera, and some mollusks).

Similarly, dissolved CO2 in the oceans can precipitate to form calcite, which is then deposited on the plate and likewise recycled into the mantle.»

At some times of year, acidification has already reached a critical threshold for organisms living on Alaska's continental shelves.145 Certain algae and animals that form shells (such as clams, oysters, and crab) use carbonate minerals (aragonite and calcite) that dissolve below that threshold.

Calcite - A calcium carbonate (limestone) mineral, used by shell - or skeleton - forming, calcifying organisms such as foraminifera, some macroalgae, lobsters, crabs, sea urchins and starfish.

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