210 On a Series of Calderite Rocks. [No. 2. 



No. 12. — Has the appearance of a resinous pitchstone : That is to 

 say, it is resinous on some fractures and on others almost a pitchstone 

 in appearance. 



No. 13. — This last is almost a black and brown, narrow-banded, 

 Jasper in external appearance, but on the fresh transverse fracture it 

 shews a very distinct granular resinous structure and aspect. The 

 tendency of fracture (or of cleavage) is however distinctly in the planes 

 of the laminae, and when even a minute splinter is held to a strong 

 light the arrangement of the imbedding of the black mineral in the 

 yellow brown quartz is distinctly seen to be horizontal and parallel like 

 the bands on the larger surfaces. 



The mineral geologist will, I trust, from these descriptions, be 

 enabled to identify this curious rock wherever he may meet with it in 

 any of its varieties ; and the importance of mineralogy to geology is now- 

 a-days, too well recognised for me to doubt that, to all lovers of scien- 

 tific accuracy this paper will be acceptable. We are moreover, in 

 India especially, bound when we bring forward any novelty to shew as 

 clearly, and in as full detail as we can, the grounds on which we do 

 so, as we thus advance the cause of science when we are right, or obtain 

 the correction we need if wrong. 



