60 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
micas,—namely, the dearth of information accorded to us by them, relating to 
the special rocks in which minerals are found, and also as to the other mineral 
species which are associated with them. 
Even the ponderous and classical work of Dana tells us no more than the 
following :— 
Penninite, “ with serpentine ;” 
Ripidolite, “in connection with chlorite and talcose rocks in schists and serpentine ;” 
Chlorite, “ same as for ripidolite.” 
There is certainly no geognostic distinction in this, and the evidence of the 
specimens analysed by me, so far from importing more precision, has an opposite 
effect; for, while it widens the geognostic scope of the occurrence of these 
minerals, it does so at the cost of opening up the habitats very much to each 
and all. 
I speak only from evidence drawn from specimens actually analysed, and 
the record runs thus :— 
Penninite,—serpentinous belt in hornblendic gneiss ; ditto in mica slate; in 
serpentine ; pseudophite in uralitic diorite. 
hipidolite, in actynolitic belt in hornblendic gneiss ; in steatitic belts in 
chlorite slate ; in granular limestone in mica slate. 
Chiorite, in serpentinous belt in mica slate; in intrusive granite; in quartzose 
belts in mica slate ; in granular limestone ; in mica slate and gneiss. 
Were we to lay weight upon numerical evidence, or frequency of occur- 
rence in each rock, we should have to make the record more confusing still, by 
saying that chlorite most frequently affects granular limestones and quartzose 
belts ; while penninite and ripidolite affect “ chloritic rocks.” 
Premising then in these general remarks that the fine-grained varieties are 
arranged in virtue of their chemical features, I now give the analyses of each, 
considering the three more important species first. 
Arranged in the order of their content of silica, they stand as on page 58. 
PENNINITE. 
From Serpentine in Hornblendic Gneiss. 
1. From the island of Scalpa or Glass, near Harris. 
A small promontory and a short stretch of the adjoining eastern coast of 
this island consists of a bed of serpentine ; this is regularly interstratified with 
