
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 261 
contact mineral. There is an approach to Saussurite in this composition, and 
in gravity. 
From Gabbro. 
2. This specimen was sent me by Mr Grirve of Kirkbank, Burntisland ; it 
was broken out of the diallagic rock at Lendalfoot, Ayrshire. 
It consisted of imbedded crystals about. half an inch in size, which were of 
a greyish-white colour, distinctly and coarsely striated, and of specific gravity 
2°761. . Sa 
1-205 grammes yielded — 
Silica, ; , 5 , » 442924 
Alumina, . : 4 Ruse ot g442 
Ferric Oxide, : P eet hhc CRG 55 
WiROMesioma) Tecan, tl ae eee 
Lime, ; ; : Als 
Potash, , : : : Ye 
Soda, : i Pele ss , P3625 
Water, 4° 023 3° 348 av. 3° 686 

99 + 592 
4 023 per cent. of the silica were insoluble ; possible impurity, diallage. 
Mr Grieve remarked to me on the fact of the diallage of this rock weather- 
ing so much more rapidly than its felspar, as to leave the latter protruding from 
the surface ; while in the compound which occurs a mile north, at Pinbain, the 
diallage is the mineral which endured, and is left protuberant. I find the 
mineral which is associated with the diallage at Pinbain to be a hydrated Saus- 
surite. The weathering at Lendalfoot is due to subaerial,—that at Pinbain to 
subaqueous action. The general rule is that in gabbros, the felspar weathers 
much the faster, but elsewhere in Scotland the felspar is labradorite. 
From Granular Limestone. 
3. I doubt if the next substance should be classed here ; it was found at 
the top of the limestone quarry at Delnabo, Glengairn, at the contact of the 
| lime with the gneiss. 
It consisted of a band about two inches thick, of a granular translucent pale- 
green substance, somewhat resembling prase,—except in its granular struc- 
ture, and its hardness, which was only about 6. It was associated with Latro- 
VOL, XXVIII. PART I. Pony 
