• WordNet 3.6
    • n silica a white or colorless vitreous insoluble solid (SiO2); various forms occur widely in the earth's crust as quartz or cristobalite or tridymite or lechatelierite
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Webster's Revised Unabridged Dictionary
    • n Silica (Chem) Silicon dioxide. It constitutes ordinary quartz (also opal and tridymite), and is artifically prepared as a very fine, white, tasteless, inodorous powder.
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Century Dictionary and Cyclopedia
    • n silica Silicon dioxid (SiO2), or silicic anhydrid, a white or colorless substance, nearly insoluble in water and in all acids except hydrofluoric acid. Silica is extremely hard, and fuses with difficulty in the oxyhydrogen flame to a colorless amorphous glass. In nature, as quartz, it is universally distributed, and is the commonest of minerals; here belong the varieties rock-crystal, amethyst, chalcedony, agate, carnelian, onyx, jasper. flint, hornstone, etc., which differ in degree of crystallization and in purity, and hence in color. Silica in the form of quartz makes the sand of the seashore, and rock-masses as quartzite and sandstone. It also occurs us the rare mineral tridymite, known only in volcanic rocks anil in a few meteorites, and as the amorphous opal, which is softer and more soluble than quartz and contains more or less water. (See quartz, tridymite, opal, also asmanite, cristobalite, melanophlogite.) Silica also forms the material of the spicules of many sponges and of the frustules of diatoms; deposits of the latter are not uncommon under peat-swamps, and in some regions vast beds have been accumulated. (See infusorial earth, under infusorial.) Silica combines with bases to form compounds called silicates, which constitute the rocky crust of the globe. It occurs in solution in the waters of many mineral springs, and sometimes is deposited in enormous quantities about geyser-basins. From the silicates taken up by plants silica is often deposited on the surface or in the interior of their stems. The value of the equisetum, or scouring-rush, is due to the silica contained in it, which sometimes amounts to 18 per cent. of the fresh plant. Sand is extensively used for the manufacture of glass and mortar. The prominent silicates recognized among minerals are the metasilicates, salts of meta-silicic acid (H2SiO3), and orthosilicates, salts of orthosilicic acid (H4SiO4). Examples are rhodonite, or manganese metasilicate (MnSi03), anil willemite, or zinc orthosilicate (Zn2SiO4). There are also disilicates, polysilicates, etc., but they are rarer, and their nature is less clearly understood. See glass, mortar, and s and. Also called silex.
    • n silica Silica fused by the oxyhydrogen blowpipe may be worked in the plastic state, very much as glass is, and retains its amorphous character on cooling. Extremely delicate threads of this material may be drawn, and are used to suspend minute, readily mobile mirrors or other such parts of physical apparatus; they are also valuable as electrical insulators, being less affected by atmospheric moisture than threads of glass. Tubes, flasks, and beakers of moderate size have also been made from fused silica, and are useful on account of the hardness of the material, the high temperature it will bear without melting, the rapid changes of temperature it will sustain without cracking, and its superior resistance to most chemical reagents. Its behavior as respects dilatation by heat is also important. Berthelot has, however, recently shown that it is permeable by gases, particularly at high temperatures.
    • n silica Same as siliqua, 6.
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Chambers's Twentieth Century Dictionary
    • n Silica sil′i-ka silicon dioxide, or silicic anhydride, a white or colourless substance, the most abundant solid constituent of our globe, existing both in the crystalline and in the amorphous form, the best examples of the former being rock-crystal, quartz, chalcedony, flint, sandstone, and quartzose sand; of the latter, opal
    • v.i Silica to become silicious or flinty:—pr.p. silic′ifying; pa.p. silic′ifīed
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Webster's Revised Unabridged Dictionary
NL., from L. silex, silics, a flint


In literature:

The converter is built of steel and lined with silica.
"An Elementary Study of Chemistry" by William McPherson
The most important determinations for these are total alkali and silica.
"The Handbook of Soap Manufacture" by W. H. Simmons
I examined a brick or two as well; they were silica, and old as creation itself!
"A Martian Odyssey" by Stanley Grauman Weinbaum
They contain silica, alumina, potash, soda, and mica mixed mechanically together.
"Fragments of science, V. 1-2" by John Tyndall
Many of these knives have silica blades, some of the handles being of jade.
"Chats on Household Curios" by Fred W. Burgess
Silica, oxyd of iron and alumina are thus dissolved.
"Peat and its Uses as Fertilizer and Fuel" by Samuel William Johnson
Silica is ordinarily looked upon as one of the most insoluble of substances.
"The Book of the National Parks" by Robert Sterling Yard
Others are almost exclusively made of silica.
"Special Report on Diseases of Cattle" by U.S. Department of Agriculture
They contain very much silica, sometimes even forty per cent.
"The Galaxy, Volume 23, No. 2, February, 1877" by Various
This is owing to the hard particles of silica which it contains.
"The Elements of Agriculture" by George E. Waring

In news:

You May Want To Use Silica For Teeth.
Silica has new plant manager & new directions.
Since mid-July, US Silica has had a new plant manager in Berkeley Springs.
Are silica gel packets harmful to the environment.
Bell makes agreement with US Silica .
One-On-One: Regulating silica 'frac' sand mining.
How Has Fracking Transformed US Silica .
Silica Dust at Dangerous Levels in Manhattan Subway.
Silica started selling stock on the New York Stock Exchange on February 1.
The dream of a new Berkeley Springs senior center is coming true with Senior Life Services of Morgan County's purchase of the former US Silica corporate headquarters.
Adding silica sand or boiler slag to pavement sealer can improve the sealcoat.
Formally celebrated the official opening of its Qingdao silica plant with a special ceremony Sept 2.
Eka Chemicals said that it has signed an agreement to acquire the silica sol business of H.C. Starck Group (Germany), known under the brand name Levasil.
This analyzer provides accurate monitoring of a wide range of silica concentrations from 0-5,000 parts per billion.
Novel Silica Cleansing Particles With and Without Sensory Properties.

In science:

Yet, in silica the BP evolution upon increasing the density has been studied experimentally and in simulations .
Boson peak in an harmonic scalar model
It was chosen because of its suitability for low momentum particle identification (range ≈0.5-4 GeV kinetic energy per nucleon). 2) Silica aerogel (AGL).
Experimental study of a proximity focusing Cherenkov counter prototype for the AMS experiment
Experimental silica samples, however, freezing in at the calorimetric Tg , do not show a high number of defects .
What is moving in silica at 1 K? A computer study of the low-temperature anomalies
Bioconjugated silica nanoparticles: development and applications.
Carbon Nanotubes in Biology and Medicine: in vitro and in vivo Detection, Imaging and Drug Delivery
The beam combiners are made by depositing alternatively 3 doped silica layers on a silicon substrate.
An integrated optics beam combiner for the second generation VLTI instruments