BARYTA. 205 



Composition. Sulphuric acid 34.00, baryta 66.00. But it often contains foreign sub- 

 stances. Formula BaO.SOa. 



Uses. Heavy spar may be employed for obtaining the other salts of baryta. It is also of 

 considerable value as a paint. When it is of a white colour, it may be used as a substitute 

 for vrhite lead, for ordinary purposes. The white lead of commerce is often adulterated with 

 it, and it is extremely difficult to detect the adulteration (see page 61). It is, moreover, 

 sometimes employed as a flux. 



Geological Situation. It usually occurs in veins, either alone, or associated with various 

 metalliferous formations of silver, copper, lead, etc. In this State, it is most commonly 

 associated with calcareous spar, forming small veins or geodes. 



localities. 



Columbia County. At the Ancram lead mine, it has been found in veins of considerable 

 thickness in the slate and limestone. It is of a white colour, and massive. I am not aware 

 that it h asbeen obtained here in the form of crystals. 



Greene County. It is said to have been found in Catskill, two miles east of the mountains, 

 associated with carbonate of copper and quartz ;* but I have no knowledge of the locality. 



Herkimer County. Near the villages of Little-Falls and Fairfield, lamellar masses of 

 heavy spar are found, having a yellowish white colour. When rubbed to powder in a mortar, 

 it gives out a strong smell of sulphuretted hydrogen. It has been noticed as a distinct variety, 

 under the name of Fetid Heavy Spar. 



In the calciferous sandrock on the south side of the Mohawk, opposite Little-Falls, there 

 occur veins and geodes of this mineral in a crystallized form. The colours are white and 

 bluish-white ; and it is sometimes translucent, or nearly transparent. The specimens are 

 fetid when rubbed or struck briskly with a hammer. The accompanying figures represent 

 the crystalline forms which have here been observed. 



Fig. 30. 



Fig. 31. 



Fig. 32. 



Fig. 30. A minute flattened table of the primary form. 



Fig. 31. The primary, with two acute solid angles replaced by planes. P on o 137° 5' 13" ; 

 o on o 105° 49' 34" {Haiti/). 

 Fig. 32, epointee of Haiiy. V ond 140° 59' 21" ; dond 78° V 58". 



' American Journal qf Science, IV. 2S0. 



