157 



The variety known as nail-head spar may be described as 

 consisting of flattened rhombobedral crystals. 1308, Weardale 

 (Bng.), and 260, AVallsend Colliery, are illustrations. 



Blach Oalcite : IJillgrove and AVilli Willi, Macleay Eiver. 



Safin Spar : fibrous calcite. 7747, Grunnedah, occurring as 



veins in basalt ; polished. 



Fcrro-calcite: carbonates of lime and iron, 9019, Boggabri ; 

 in basalt, 10151, Tullamore. 



Fine specimens of calcite are exhibited from IJ'rizington, Cum- 

 berland (Eng.), the Weardale Lead Mines (Eng.), and the 

 Jenolan Caves. 



3844, a curious botryoidal form, from Oregon. 



A special exhibit of stalactites of carbonate of lime from the 

 Limestone Caves is contained in case 134. 



Larger specimens of calcite will be found in caS3S 125 and 121. 



A B 



Crystals of Calcite. 



A. Rhomboliedron. 



B. Scalenoliedron. 



C. Prism with rhomboliedron. 



Carbonate of lime. Aragonite differs from calcite in hardness, Aragonite. 

 specific gravity, and system of crystallization. The best crystals 



