BARYTES, or BARYTA, the Oxide of Barium. The Oxide of Barium is found in the earth in combination with acids, principally the sulphuric and carbonic.
Native Sulphate of Barytes, known by the name of Henry Spar, also Hepalite and Bologna Spar, presents itself in various forma, as crystal line, fibrous, snecharoid, compact, and earthy. The crystals are usually tabular, in modified rhombic and rectangular prisms. Its degree of hardness is from 3 to and the specific gravity from to Some varieties are fetid when rubbed. It is composed of sulphuric acid 34, and barytes 66. It decrepitates before the blowpipe, and fuses with difficulty. It is distinguished by its heavy specific gravity from Cdcstine and A rragonite, and from the various carbonates by not effervescing with acids. Heavy Spar is often associated with the ores of other metal& This substance is much used in tho arts. It is ground up and used as white paint, and also for adulterating white lead. Mixed with equal parts of white lead, it is sometimes called Venice White; and another variety, with twice its weight of barytes, is called Haniburgh White; and another, one-third white lead, is called Dutch White. The ' barytes in these mixtures seems to prevent the white lead from being tarnished by mulphuretted hydrogen, and they are therefore preferred for some kinds of painting. The variety called Bologna Spar is highly
phosphorescent after calcination. Allomorphite is a synonym of Heavy Spar. Cawk is a massive variety. Dredite is a sulphate of barytes and lime.
Native Carbonate of Barytes, Witherite, Barolite, is remarkable for its high specific gravity, being P3. It is prismatic, and occurs generally in 6-aided prisms, or modified rhombic prisms, very imperfectly cleavable. It is also found in globular botryoidal shapes, showing a prismatic structure. It is brittle, and decrepitates before the blow pipe, fusing easily into a transparent globule, which becomes opaque on cooling. It effervesces with nitric acid, and is composed of barytes, and carbonic acid, 22.4. It is found chiefly at Alston Moor in Clumberlmid, and Anglezarke in Lancashire, and also in Styria.
IViI/serite is a poisonous mineral, and is need for killing rata It is also employed in pyrotechny for making the nitrate which gives a yellow colour, and it is used as a water-colour. Beryto-Calcite and Bromlite are varieties, the former from Alston Moor in Cumberland, the latter from Bromley IlilL They consist of the carbonate of lime and barytes Sulphate-Garbonatc of Barytes is a variety containing the sulphate of,barytes.
(Dana, Manual of Mineralogy.)