102 



A. H. Hunt — Age of the Dartmoor Granites. 



The particular point I desire to emphasize on the present occasion 

 is the intimate association in the Dartmoor area of fluid inclusions, 

 containing cubic and other crystals, with fluid inclusions consisting 

 apparently of plain water. 



Fig. II. 



Fig. III. 



j 3*;,.i <,'.;f 



'■■•<-'■'■'■ b-"" 



©r^ 



^ (!::=> ^' 3 







=^cs:)@ ji 



ii- 



In a slice of a veinstone from near Manaton there is an hexagonal 

 crystal of quartz about -3-0- inch in diameter. The gradual growth 

 of this crystal is defined by tourmaline and tourmaline microliths.^ 

 It is crowded with inclusions, both irregular and with crystalline 

 outlines {i.e. negative crystals). We can see that it has never been 

 viscid, plastic, or colloid, or anything else than a mineral gradually 

 crystallized out from solution. 



Within this crystal, and not more than -g-oo^o-o" inch apart, there 

 are two inclusions, both of them negative hexagons, with small 

 bubbles : but one contains a cube, and the other contains none. There 

 is also a negative hexagon with a relatively large bubble, -niVo inch 

 distant from an irregular inclusion with a very minute bubble. 



Among the liquid inclusions, as figured above (Fig. II.), there is a 

 tourmaline microlith which seems to have caught up a cube of some 

 chloride during crystallization. The inclusions drawn are selected, 

 and not in their relative positions, excepting the two couples within 

 small circles. 



^ See Trans. Devon. Assoc, vol. xxi. p. 261, plate, fig. 3. 



