500 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Figs. 104, 105. Stone-cavities in the quartz of an elvan near Penrhyn, Cornwall. 

 104, X250; 105, X800. 



Fig. 106. A stone-cavity attached to a crystal of schorl in the quartz of an elvan 

 near Penrhyn, Cornwall. X400. 



Fig. 107. A stone-cavity attached to a vapour- or gas-cavity in the quartz of an 

 elvan near Gwennap, Cornwall. X 800. 



Fig. 108. A fluid-cavity in the quartz of an elvan near Gwennap. X 2000. 



Figs. 109, 110. Fluid-cavities in the quartz of an elvan near Gwennap, enclosing 

 or attached to crystals of schorl. X1200. 



Fig. 111. A portion of the quartz of the granite at St. Austel, Cornwall, X 200, 

 with many fluid-cavities, and one vapour- or gas -cavity. 



Fig. 112. A fluid-cavity in the felspar of the granite at Penrhyn, Cornwall. 

 X1600. 



Fig. 113. A fluid-cavity in the mica of a granite-vein at Polmear Cove, Corn- 

 wall. X1600. 



Figs. 114, 115. Fluid-cavities in the quartz of the granite from the Ding Dong 

 Mine, near Penzance. 114, X2000; 115, X800. 



Fig. 116. A fluid-cavity in the quartz of the main mass of granite at Aberdeen. 

 X2000. 



Fig. 117. A stone-cavity in the quartz of the granite at St. Austel. X 1000. 



Fig. 118. A stone-cavity in the quartz of a rather coarse-grained granite near 

 Cape Cornwall. X 800. 



Fig. 119. A stone-cavity in the quartz of the gramte at St. Austel, with ra- 

 diating cracks. X 600. 



Fig. 120. A stone-cavity in the felspar of the granite at Lamorna, near Pen- 

 zance. X800 



