404 SKY. MINERALS. 



In this latter state, when minute, they sometimes transmit 

 the black colour of the subjacent basalt to which they 

 adhere, so perfectly as to present a velvety surface 

 of black crystals. In similar circumstances, transmit- 

 ting the greyish or ochrey tint of the substance to 

 which they are attached, they appear to possess a 

 colour which a more narrow inspection shows to be 

 fallacious. A few specimens occur of a flesh red, a 

 colour frequent in almost all the minerals of this family, 

 and very predominant in the different zeolites which are 

 found at Glen Farg in Perthshire. I also observed a 

 solitary specimen of a pale sea green hue, and I may 

 add that a brick red variety, but uncrystallized, occurs 

 in the amygdoidal rock near Loch Brittle. 



Chabasite is found in similar circumstances on the same 

 shore, but is comparatively of very rare occurrence : it 

 is common however in the rocks at the Storr, which for 

 a considerable space consist of an amygdaloid containing 

 this substance accompanied by stilbite. It is here so 

 abundant, occupying cavities of greater or less magnitude, 

 as to form a considerable part of the total bulk of the 

 rock. 



As far as I have observed, this mineral is never, like 

 the analcime, imbedded in the filamentous nadelstein, 

 but it is not unfrequently associated in the same cavity 

 both with stilbite and with analcime ; nor is it unusual 

 to find minute and well formed crystals of this latter 

 substance, imbedded in the crystal of chabasite. In 

 some cases perfect crystals of chabasite are lightly sprinkled 

 over the surfaces of crystals of stilbite, adhering so slightly 

 as to fall off on the slightest concussion : in others, crystals 

 of this mineral, as well as of the analcime, are confusedly 

 mixed with the rhomboids of carbonate of lime hereafter 

 to be described. 



The primitive crystal is by much the most com- 

 mon, the modifications being rare and offering few 

 varieties; but it is very frequently twinned, the angles 



