PHYSIOGRAPHY. J 05 



Calcareous Spar. 



Fig. 121. 

 Fig. 120. 



In Fig. 116 and 117 the face of composition is perpen- 

 dicular to the axis of the aggregated crystals ; and the an- 

 gle of Revolution =60. In Fig. 119 the face of compo- 

 sition is represented by the dotted lines in Fig. 118. In 

 Fig. 120 it coincides with a plane passing through its verti- 

 cal axis : in both, the angle of revolution = 180. The 

 regular composition in faces parallel to the plane indicated 

 in Fig. 118, takes place also in massive varieties ; and then 

 more or less thick laminae of the two individuals alternate 

 with each other, as in Fig. 121. The frequent occurrence 

 of those well known striae (here delineated) upon the faces 

 of cleavage, parallel to the horizontal diagonal of the 

 rhombs, depehds upon this mode of regular composition. 



Implanted globules ; stalactitic, botryoidal, fructicose 

 shapes : surface uneven, drusy, rough or smooth, composi- 

 tion columnar, more or less distinct, straight diverging, and 

 of various sizes. Sialactitic and botryoidal varieties are of- 

 ten composed a second time of curved lamellar particles, 

 conformably to the surface of the imitative shapes, the faces 

 of composition being uneven and rough, or irregularly 

 streaked in a longitudinal direction, 



