Barium minerals

Strontian, town in Scotland) Isolated by Davey by electrolysis in 1808 however, Adair Crawford in 1790 recognized a new mineral (strontianite) as differing from other barium minerals. 

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. 

Alchemists in the early Middle Ages knew about some barium minerals. Smooth round pebble-like stones found in Bologna, Italy, were known as Bologna stones. When these odd stones were exposed to sunlight, or even a primitive reading lamp, they would continue to glow for several years. This characteristic made them attractive to witches as well as the alchemists. These stones are actually the mineral barite, barium sulfide (BaSO ), which today is a major source of barium metal. 

William Cruickshank in 1787 and Adair Crawford in 1790 independently detected strontium in the mineral strontianite, small quantities of which are associated with calcium and barium minerals. They determined that the strontianite was an entirely new mineral and was different from baryta and other barium minerals known at the time. In 1808, Sir Humphry Davy isolated strontium by electrolysis of a mixture of moist strontium hydroxide or chloride with mercuric oxide, using a mercury cathode. The element was named after the town Strontian in Scotland where the mineral strontianite was found. 

Seaton A, Ruckley VA, Addison J, et al. 1986. Silicosis in barium miners. Thorax 41 591-595. 

Barium Minerals Barite (BaS04) and witherite (BaCOs) are commonly used to supply barium in ceramic formulations. Purified barium carbonate, made by dissolution and repredpitation, is used most frequently in ceramic processes and as fluxing compounds in the grazes, ass, and enamels of electronic ceramics and in heavy day products to prevent scumming. The use of these minerals have the drawback that upon heating they give off gas, which can cause cracks. 

But Crawford found that some of the minerals did not behave as he expected. They did not have the properties of barium minerals. He concluded that the minerals contained a new element. He called the element strontia. He named it after a lead mine in Strontia, Scodand, from which... 

The most important barium mineral is heavy spar (BaS04, barite), whose deposits are distributed over the whole world. Worldwide extraction in over 30 countries was 4.4 10 t/a in 1995, of which 1.5 (O t/a was produced in China, 0.58 10 t/a in India and 0.54 lO t in the USA. In the Federal Republic of Germany the production of marketable raw heavy spar and the quantity of processed heavy spar were together 0.15 I O t/a in 1995. The worldwide production peaked in 1981 at 8.3 10 t/a, which is about double the 1995 production of 4.4 10 t/a. This decline was mainly due to less exploration and drilling. The worldwide reserves of heavy spar have been estimated to be ca. 1.8- 10 t, of which 0.17 10 t are certain. 

The most important barium minerals are barite (BaS04) and witherite (BaCOj) (Greenwood and Earnshaw 1988). Other minerals are hollandite (Ba2Mn80i,) and psilomelane ((Ba,Mn)3(0,0H)8Mn80i8). Potassium feldspar (KAlSijOg) and biotite (K(Mg,Fe)3((OH,F)2/AlSi30io) contain low amounts ofbarium (0.3% and 0.11% respectively), but are important with regard to the total amount ofbarium in the Earth s crust, which has been assessed as either 260 mg kg (Holleman et al. 1995) or... 

Barium, as well as his analogues in the second group of the periodic table, is not encountered in nature in the native state. Sulphates and carbonates are the most typical barium minerals. One of barium minerals attracted attention of alchemists back in the early 17th century (in 1602, to he exact). 

In 1787 a new mineral, strontianite, was found in a lead mine near the village of Strontian in Scotland. Some mineralogists classified it as a variety of fluorite (CaFj). The majority of scientists, however, believed that strontianite was a variety of witherite (barium mineral BaCOg). 

A barium mineral was dissolved in hydrochloric acid to give a solution of barium ion. An excess of potassium sulfate was added to 50.0 mL of the solution, and 1.128 g of barium sulfate precipitate formed. Assume that the original solution was barium chloride. What was the molarity of BaCl2 in this solution ... 

---