108 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
Or generally— 
6R Si + R, Si+ 13 H,. 
Or atoms— 
RG) Real Sy as: 
Celadonite. 
Atoms. 
Silica, ; »  yil 3 Bat Waroyakes Tess 18} 8 54:05 
Alumina, . iy NOT 3°83 
Ferric Oxide, . 12°64 "1585 ABS net eto 
Ferrous Oxide, 4:9 136 4. 
Magnesia, . 6°57 : wo TOG 9 3 3 6°76 
Potash, . ~ 165 *148 7°88 
Water, 9-84 EO Soleo. 2oa> 10°14 
Formula— 
(Fe! Mg? K,#)? Si* + (Al,! Fe’) SP + 5H,. 
Or generally— 
3(R Si) + R, S? + 5H). 
Or atoms— 
RS Rela Gus, El, 5: 
In the above investigation every substance, the nature of which was at all 
doubtful, of which I could obtain a sufficiency for analysis was examined. 
In applying the results of the examination to the consideration of the geog- 
nostic relations of these minerals, those of the first or true chlorite type may 
be dismissed in few words. 
With the exception of the occurrences of chlorite at the Girdleness and at 
Rubislaw in granite, the minerals of the first class are to be found only in 
metamorphic rocks. 
Glauconite, occurring generally in rock which is believed to be of recent 
origin, may, by its occurrence, aid somewhat in the assigning the age of certain 
doubtful strata. 
The second group, which I have called the saponites, belong solely to 
igneous rocks; and, from the mode of their occurrence, there is no room for 
doubt that they result from the alteration of certain of the constituents of these 
rocks—augite and olivine in all probability. 
As regards our power of distinguishing them from each other, this is by 1 no 
