398 DETERMINATION OF MINERALS. 



ARAGONITE, p. 218. H.=35-4; G.=2.94; trimetric, cleavage im. 



perfect ; otherwise like caleite. 

 DOLOMITE, p. 219. H. =3-5-4 ; G ,=2'8-2-9 ; rhombohedral, RAR 



= 106 : 15' ; colors various ; effervesces but slightly with cold HC1, 



unless finely pulverized ; anhvdrous. 

 MAGNESITB. p. 207. H. =3 5-45 ; G. =3-31 ; rhombohedral, J? A R 



= 107' 29' ; white, ywh, gyh ; effervesces but slightly with cold 



HC1 ; anhvdrous. 



H.=l-3 5 ; G. =2 14-218; hydrous. 



B. INFUSIBLE ; BECOME MAGNETIC AND NOT ALEALLNE AFTER 

 IGNITION. 



SIDERITE, p. 185. H. =3 5-45; G. =3-7-3-9; rhombohedral, R:R 

 = 107 : ; cleavage as in caleite ; becomes brown on exposure, chang- 

 ing to limonitf. 



ANKERITE, p. 186. H.=3'5-4; G.=2'9-3 1 ; i?Ai2=106 3 7' ; be- 

 comes brown on exposure. 



Some kinds of caleite and dolomite contain iron enough to become 

 magnetic on ignition. 



C. INFUSIBLE ; B.B. ON COAL WITH SODA, COATING OF ZINC OXIDE. 



SMITH SONITE, p. 156. H.=5; G.=4-4 5; rhombohedral like 

 caleite; R \i?=107 40 ; crystals often an acute rhombohedron ; 

 anhvdrous. 



HYDROZINCITE, p. 157. H. =2-2*5; G. =36-3 8; white, gyh, 

 ywh, often earthy ; reacts for zinc ; hvdrous. 



D. INFUSIBLE ; B.B. ON COAL REACTION FOR NICKEL. 



ZARATITE (Emerald nickel), p. 168. H.=3. Emerald green, streak 

 paler. 



E. FUSIBLE : ASSAY ALEALLNE AFTER IGNITION. 



WITHERTTE, p. 221. H. =3-3-75 ; G. =4 29-4-35 ; trimetric ; white, 



ywh, gyh ; B.B. fuses easilv, flame vwh green ; anhvdrous. 

 STRONTIANITE. p. 223 H. =35-4 ; G.=3 6-372 ; trimetric ; pale 



freen, gray, ywh, white ; B.B. fuses only on thin edges, flame 

 right red ; anhvdrous. 

 EARYTOCALCITE, p. 222. Monoclinic. G. = 36 3'66 ; B.B. nearly 

 like witherite. 



Other carbonates are the Lead Carbonate, p. 152, and Copper Car- 

 bonates, p. 140. included severally under the heads of Lead and Cop- 

 per, on page 391. 



