ORDER I. MACROTYPOUS LIME-HALOIDE. 97 



are soluble in acids, but more slowly than the preceding 

 species, and they produce a much slighter effervescence. 

 Before the blowpipe some of them assume a darker colour 

 and a higher degree of hardness. 



3. The different varieties of macrotypous Lime-haloide 

 are likewise different in respect to their localities ; and 

 this, in fact, seems to have had some influence in the older 

 determinations of the species. Dolomite constitutes beds 

 in other rocks, and belongs therefore itself to the class of 

 rocks. Rhomb-spar occurs in imbedded crystals and compound 

 masses in several kinds of rocks, particularly in common 

 talc, which is a variety of prismatic Talc-mica : less fre- 

 quently in compact varieties of prismatic Gypsurn-haloide 

 that are mixed with clay. Brown-spar is principally found 

 in metalliferous and other veins, where it is accompanied 

 by several species of Glance, Blende, Pyrites, &c. and 

 assumes various imitative shapes. 



4. Dolomite occurs in St Gotthard, in the Appenines, in 

 Carinthia ; Ilhomb-spar in various districts of Salzburg, 

 the Tyrol, and Switzerland, at Miemo in Tuscany, from 

 which the name of Micmite has been derived ; and in many 

 other countries ; beautiful crystals at Traversella in Pied- 

 mont. Brown-spar is very frequent at Schemnitz in Hun- 

 gary, Kapnik in Transylvania, Freiberg and other places 

 in Saxony, at Clausthal in the Hartz, in Norway and Swe- 

 den, at Alstonmoor in Cumberland, in the greywacke- 

 quarries of the same country, in Derbyshire, Beeralston 

 and other places in Devonshire, &c. It is as difficult to 

 form a decided opinion on the geological and geographical 

 distribution, as on the chemical composition of any spe- 

 cies, if the varieties of other species have not been distin- 

 guished from it with a sufficient degree of accuracy. 



5. Several varieties of Dolomite, among which the Pa- 

 rian marble seems to be according to the specific gravity 

 quoted, are used in sculpture ; they are said to be particu- 

 larly durable. 



VOL. II. G 



