Calcium spar

Iceland spar, see Calcium carbonate lodyrite, see Silver iodide... 

Most of the acid-grade spar used for HF production ia the United States is imported. More than two-thkds of the fluorspar consumed ia the United States goes iato production of HF nearly 30% is consumed as a flux ia steelmaking and the remainder is consumed ia glass manufacture, enamels, welding rod coatings, and other end uses or products (see Fluorine compounds, inorganic-calcium). 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

Synonyms anhydrous calcium sulfate-anhydrite muriacite karstenite anhydrous gypsum anhydrous sulfate of lime hemihydrate-plaster of Paris annalin dried gypsum dried calcium sulfate dihydrate-gypsum alabaster satin spar mineral white terra alha satinite light spar selenite precipitated calcium sulfate native calcium sulfate... 

In 1768 A. S. Marggraf made the first chemical investigation of fluorite, distinguished it from heavy spar and selenitic spar (sulfates of barium and calcium), and showed that it is not a sulfate (77, 78). When he distilled pulverized fluorspar with sulfuric acid from a glass retort, the glass was badly attacked and even perforated. He noticed that an earth [silica] appeared in the receiver, and therefore concluded that the sulfuric acid had liberated a volatile earth from the fluorspar (77). 

Acute scalcntihcdral crystals are sometimes referred to as dogtooth spar. Calcite represents the stable form of calcium carbonate aragonite will go over to calcite at 470 C (K78=F. Calcite is a common constituent of sedimentary rocks, as a vein mineral, and as deposits from hot springs and in eaves as stalactites and stalagmites. 

Yellow ochres are earths composed essentially of clay coloured by hydrated ferric oxide they may contain siliceous sand, calcium carbonate, small proportions of manganese oxides, and sometimes basic ferric sulphate and calcium and barium sulphates. Chalk, gypsum and heavy spar may be added fraudulently and the colour may be " improved by artificial organic dyes, vegetable colours or chrome yellow. 

Minium may contain various impurities derived from the raw materials of its manufacture, e.g., calcium salts and oxides of iron and copper. It may be adulterated with day, chalk, gypsum, heavy spar, lead sulphate, brickdust, ochre and other colours with a basis of ferric oxide, and artificial organic dyes. 

Ca(OH)2.Aq + 2HBr.Aq = CaBr2.Aq + 2HaO. These salts are also white and soluble in water. There is, however, one exception, namely, calcium fluoride, CaF2, which occurs native as fluor- or Derbyshire spar. It forms colourless cubical crystals, and is the chief compound of... 

Thus, water containing HC03 indicates C02-indueed interactions with rocks, and the balancing cations indicate the types of rocks passed calcium comes from interaction with limestone, and calcium and magnesium together come from interaction with dolomite potassium and, even more often, sodium in bicarbonate water come from silicate rocks rich in potassium or sodium feld-spars. 

This can be prepared in several different ways. Commonly dry Castile soap is dissolved in 80 per cent, alcohol in such proportions as will yield a solution well above the desired final concentration 100 grams per litre is a convenient ratio. After allowing this solution to stand at rest for several days for the deposition of undissolved matter, a quantity of the clear liquid is withdrawn (usually 75-100 c.c. per litre of final solution), and so diluted with 80 per cent, alcohol as to produce a solution which on titration with a known weight of calcium chloride solution under the standard conditions will give results in accordance with Clark s table. The calcium chloride solution is best prepared by dissolving 0-2 grams of Iceland spar in dilute hydrochloric acid excess of acid is removed by evaporation on a water bath and the solution then diluted to 1 litre with distilled water. A mixture of 25 c.c. of this solution, mixed with 25 c.c. of water, should require 7-8 e.e. of Clark s standard solution for the production of a permanent lather. 

Some of the Group IA and IIA metals are found in nature in the form of carbonates, silicates, nitrates, and phosphates. For example, calcium carbonate is one of the most important naturally occurring compounds, and it is found in several forms. The most common form of calcium carbonate is limestone, which is used extensively as a building stone as well as the source of lime. Other forms include chalk, calcite, aragonite, Iceland spar, marble, and onyx. Many other materials such as egg shells, coral, pearls, and seashells are composed predominantly of calcium carbonate. Thus, it is one of the most widely occurring compounds in nature. 

The second example is for the precipitation of calcium carbonate from Ca(HC03)2 solutions. The mechanistic model was derived by Plummer et al. [40] from a kinetic study of the dissolution of Iceland spar crystals. The approach has more recently been extended to the interpretation of crystal growth [41]. The model is based upon the reaction between a partially dehydrated [Ca-HC03]+ complex or ion-pair and possible anionic reaction... 

Open Ocean Dissolution Experiments. The first direct studies of calcium carbonate dissolution in deep seawater were made by Peterson (41) and Berger (42). Peterson suspended spheres of Iceland spar calcite, held in pronged plastic containers, at various depths in the Central Pacific Ocean for four months. The amount of dissolution was determined by weight loss, which was small relative to the total weight of the spheres. On the same mooring Berger suspended sample chambers, which consisted of... 

SYNS ACID-SPAR CALCIUM DIFLUORIDE FLUORITE FLUORSPAR IRTRAN 3 UPARTTE MET-SPAR... 

SYNS ALABASTER ANNAUNE C.I. 77231 C.I. PIGMENT WHITE 25 GYPSUM GYPSUM STONE LAND PLASTER UGHT SPAR MAGNESIA WHITE MINERAL W HITE NATIVE CALCIUM SULFATE PRECIPITATED CALCIUM SULFATE SATINITE SATIN SPAR SULFURIC ACID, CALCIUM(2+) SALT, DIHYDRATE TERRA ALBA... 

How much calcium may be obtained from 100 gm. of (a) marble, ( ) gypsum, CaS04.2H20, ( ) fluor spar, CaF2, superphosphate of lime, CaH (POj2 ... 

At a given temperature t, this pressure has a value which does not depend upon the various peculiarities which may characterise the experiment in particular, it does not change if at the beginning of the experiment there is put into the apparatus not only Iceland spar, but also an excess of quicklime. Depending solely upon the temperature t, this pressure may be called the dissoda--Hon tendon of calcium carbonate at the temperature L... 

For more than 100 years, researchers labored without being able to identify the elements in the stone. In 1774, Scheele announced the presence of a new element in the Bologna stone. Today, scientists know that the stone was a form of barite. Five years later, Scheele demonstrated that barite was also present in heavy spar. This dense transparent mineral closely resembles ordinary spar, a compound of calcium. 

Fluorine never occurs as a free element in nature. The most common fluorine minerals are fluorspar, fluorapatite, and cryolite. Apatite is a complex mineral containing primarily calcium, phosphorus, and oxygen, usually with fluorine. Cryolite is also known as Greenland spar. (The country of Greenland is the only commercial source of this mineral.) It consists primarily of sodium aluminum fluoride (Na3ALF6). The major sources of fluorspar are China, Mexico, Mongolia, and South Africa. In 2008 in the United States, fluorspar was produced as a by-product of limestone quarrying in Illinois. The United States imports most of the fluorspar it needs from China and Mexico. 

Calcium sulfate dihydrate alabaster Cal-Tab-, Compactroh, Destab-, E516 gypsum light spar mineral white native calcium sulfate precipitated calcium sulfate satinite satin spar selenite terra alba USG Terra Alba. 

Cryolite, which is so called on account of its high fusibility, is a double fluoride of aluminium and sodium of the formula Al2Fe.6NaF. It is obtained from Western Greenland, where it occurs in beds up to one metre thick, but the high price of this material has led to the manufacture of synthetic cryolite, using calcium fluoride (fluor-spar), which is found in considerable quantities. 

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