Vol. 70.] OF THE COUNTRY AROUND HUNTLY. 283 



Dr. V. M. Goldschrnidt l seems to have found it in rocks of sedi- 

 mentary origin, the chemical composition of which was unaltered 

 by the intruded rock. The cordierite is frequently crowded with 

 inclusions, and shows signs of incipient pinitization. 



Two kinds of garnet are to be observed — the normal pink garnet, 

 ■and, associated with it, a colourless garnet that can be seen to pass 

 into the pink variety. The colourless garnet often bears vermicular 

 markings ; and the association — hypersthene, colourless garnet, 

 magnetite, pink garnet, with or without biotite and pleonaste — can 

 be observed wholly or partly developed in many of the rocks 

 where the hypersthene is undergoing change. The bigger garnets 

 are pink, and often contain as inclusions quartz, biotite, felspar, 

 and cordierite. 



The green spinel, pleonaste, is present in most slides of the 

 series, as a rule in small amount. Its colour varies considerably 

 from a pale grass-green to a dark olive-green hue. It is a common 

 inclusion in felspar and cordierite, and is grouped round the plates 

 of sillimanite. The last-named mineral is not very common, but it 

 may form either fibrous tufts of needles or fairly large plates similar 

 to those mentioned above. Magnetite, pyrite, and zircon are wide- 

 spread, while pinite occurs as an alteration -product of the cordierite. 

 Widespread also are minute intergrowths of quartz and acid felspar 

 similar to the myrmekite of the igneous rocks. 



Turning to the rocks themselves, we note that the Carvichen 

 intrusion has produced a cordierite-norite at Battlehill Quarry. 

 Veins from the granite traverse the norite here, and their effect is 

 traced in the contact-rock as a whole, which has a specific gravity 

 of 2*82 as against 2*98 for the original norite. 



In section, the ophitic texture of the norite is replaced by a 

 granular aggregate of minerals — chiefly hypersthene, felspars, and 

 cordierite. The felspars include orthoclase and labradorite (fi = 

 1*559). Both pink and colourless garnets are present, the latter 

 associated with magnetite, hypersthene, and biotite. Biotite is 

 sparingly represented, and the other accessory minerals are pyrite, 

 pleonaste, zircon, and quartz, the last-named usually occurring with 

 the garnet. The presence of quartz and orthoclase is due to 

 the influence of the granite, rather than to any rearrangement 

 ■of the molecules of the rock. 



Kound the southern and eastern boundaries of the Ordiquhill 

 intrusion occur a series of cordierite-norites and related rocks. On 

 the eastern slopes of Ordiquhill itself, the garnet-diorite portion of 

 the intrusion is in direct contact with the norite. Here the norite 

 proper is succeeded by a garnetif erous norite with granular structure, 

 wherein the comparatively large garnets are accompanied by quartz 

 and associated with hypersthene. The intruded rock is found to 

 carry, in addition to the minerals of the garnet-monzonite, some 

 strongly pleochroic hypersthene and a little cordierite — pointing to 

 an exchange of material. 



1 ' Die Kontakt-Metamorphose im Kristianiagebiete ' Yidensk. Skrift. I. 

 Mat. Naturv. Kl. 1911, No. 11, pp. 358-59. 



