NOME II. SIDERITE, WITH MICA. 4 1 



their colour under the blow-pipe, and becoming 

 white like the former, but without any further 

 change ; and they also melt with effervescence 

 in the mineral alkali, without colouring it in the 

 slightest degree. But in the interior of the stone 

 are found black and soft parts, which, when 

 moistened with the breath, exhale an odour of 

 clay, and melt under the blow-pipe. The black 

 polished parts are therefore also of quartz, or, if 

 you will, of jasper, coloured by some particles 

 of the black pierre de come, which is found in 

 the interior of the rock." 



He supposes the t the most natural explanation 

 of the polish is, that it arises from crystallisation 

 on a vast scale, as it is accompanied with streaks, 

 like those common in crystals of quartz. 



NOME II. SIDERITE, WITH MICA. 



[DEMOCRILITE, from Democritus the philo- 

 sopher, B. C. 480, who made many experiments 

 on plants and minerals.] 



The particles of siderite are sometimes inti- 

 mately blended with particles of mica. 



