536 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
magnetite, which interstices acted upon the mineral in a manner similar to the 
Feather-alum and similar salts have their peculiar form 
holes in a draw-plate. 
impressed upon them in some such way. 
ALTERATION PRODUCTS OF HORNBLENDE. 


8G. || Si | Alp. | Feo | Fe. | Mn.| Ca. | Mg. | Ky | Nap | yt 
Hydration—Loss of Ca—Peroxidation— 
Hydrated Hornblende, Greenhill, | 3°01 || 50°92] 1°89 | 9°43 | 2°09) °31 | 8°65 | 21°58) °34 43 4°54 || 100°17 
Hydrous Anthophyllite, Scoorie,. | 2°92 || 45°51) 639 | ... | 14°29) ... 4°44 | 22°14] tr. tr. 6°72 || 99°44 
Mountain Cork, Portsay, = Rae 5-43) 7°52 | 2°06 | 2°49)" 1:3 258 O35) See ... | 25°04 || 99°76 
5, Leadhills, Boe 51°45 | 7:98 97 | 3°29) 1:49 | 1°97 | 10°15 21°7 99" 
Mountain Leather, Tod Head, bss 52°48 | 6°33 6 211} 2°88 | 1°34 | 11°95 21°7 99°4 
Mountain Silk, Partan Craig, 2°11 || 54°37 | 11:27 “21 09) =33 98 | 9°49 22°41 || 100°16 
Hydration—Loss of Ca and ases— 
Passage into Serpentine— : 
Picrolite, Balta, 2°69 || 50°19 | 2-1 4°39 01 | 5°07 | 29°23 “74 8°5 || 100°28 
5 serpentinous, Balta, 2°63 || 50°08 | 1°88 6°09] ‘23 86 | 31°57 34 | 93 || 100°34 
Above,—with Removal of Silica— 
Hydrous Anthophyllite, Urquhart, | 2°81 || 47°72] 3°84 S18) 574 16 | 5°64 | 28°75) :19 26 7°65 | 10012 
Hydrous‘Asbestus, Portsoy, 2°39 || 46°92] °63 ON) Ler) 340) 9590 | 25285) en 58 | 12°84 || 9Os7b 
Picrolite, Fethaland, 2°65 || 42793 | 1°85 | 51 a “42 8 | 36°19) -81 Or Wes 99°97 
Hydrous Anthophyllite, Ayrshire, 2°81 || 39°75) °49 | 5:3 ANT) “238 | (6527 || 26:25 || “76 ‘11 | 16°83 || 10071 
Baltimorite, Killin, 2°63 || 40°47 | onc 4:01 | 4°83 26 eon | Otole = .. | 12:5 | 10am 
Chrysotile, Fetlar, ee WE eres ata Bs PLAN ae 41°61 15°66 || 100°02 
























In taking a periscopic review of the foregoing analyses, we will direct our 
attention first to the information accorded to us by an examination of the 
alteration products of these closely allied species. 
It has to be remarked, in the first place, that as the above analyses of these 
alteration products were made in the course of a progressive examination of all 
uncertain minerals, and in no way with the object of determining the nature of 
what has been unfortunately designated as “the magnesian process,” these ana- 
lyses come forward as altogether unbiassed witnesses as to what that process 
has been. They were not selected from the rock as specimens suitable or 
likely to prove any theory whatever, but were simply chosen as the best 
obtainable illustrations of things, the nature of which it was desirable to 
determine. 
The first clearly notable point is that the so-called “ serpentinous change” 
affects all the allomorphic forms of augite, the more solid and massive equally 
with the fibrous and foliaceous; while it seems for the most part inert as 
regards the denser varieties of hornblende, it being merely the fibrous and more 
delicate forms of that mineral which are affected. 
As regards the transformation itself, it has, in considering certain of the 
analyses, been pointed out, that though serpentine is generally said to result 
from a change induced in augitic minerals through the direct insertion of mag- 
