aD2 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
Let us take evidence from the specimens analysed as to these points. 
Setting aside, meanwhile, the evidence of all those fibrous hornblendes 
which occur in serpentinous rocks, which, it has been shown, may and do result 
from the metamorphosis of rocks of both a hornblendic and augitic nature,—and 
waving all present consideration of the question whether several of the rocks | 
mentioned are necessarily of an igneous origin, we come first to the hornblende 
of Balta. 
This occurs imbedded in a diallage rock, one of the augitic series, a rock in 
which there is no free silica, no orthoclase or albite; the immediate matrix is 
labradorite,—a bed of which, some dozen feet apart, also carries augite. So thus 
our first appearance of hornblende, as above noted, contradicts at once the first, 
third, and fourth of the principles laid down above. 
Next we have the hornblende of Fetlar, which with anorthite forms a well- 
marked rock. DELEssE having found anorthite in certain rocks denominated 
diorite, we grant the applicability of the name. No augitic mineral is here 
present and no quartz; but if the Balta specimens did not, in having labra- 
dorite as their associate, conform to the requirements which demanded that 
the hornblende should be accompanied by a neutral silicate, we have a further 
departure here in the presence of the most highly basic of all the felspars. 
The huge crystals of Glenbucket stand the next in order. The rock they 
go to form has labradorite as its felspar, with small quantities of other things; 
but quartz and the neutral silicates again find no place. The requirements of 
the first postulate are not here met in either particular, and it will afterwards 
be shown that this occurrence goes far to nullify the third. 
The same remarks, in their totality, apply to the hornblendic occurrence in | 
the labradoric diorite of Portsoy, our fourth example, and these are all that m | 
any way do apply. As regards postulate number one, we have had contradiction 
throughout. Three of the four cases brought forward were those of the finest 
and best developed of the occurrences of the mineral in the country. That 
which stands next in this respect, namely, the hornblende of the Deskery, 
bears evidence which is of the same character. I do not mean to insist that in 
Scotland there is never a rock association between hornblende and the more 
acidic felspars; but the syenite of Froster Hill, consisting of hornblende, 
orthoclase, and some menaccanite,—the “beautiful rock” of Colafirth, con- | 
sisting of hornblende (?) and albite,—the rock of Hillswick, of actynolitic horn- | 
blende and albite,—and hornblendic gneiss, are the only good illustrations 
which I remember where the above requirements are complied. with.* 
As regards postulate the second, it will be seen that the evidence of the 
section of the chapter which bears upon this is entirely in its favour. 
* The felspar of the Morven syenite I have not yet determined, There is also a peculiar rock 
found north of Shinness in which the felspar may be orthoclase. 

