PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 101 
13. The pathway to the Quiraing when followed northward from the last- 
mentioned locality winds round a projecting spur of rock; in this druses of 
about two inches in diameter occur, which are totally filled with saponite. Here 
its colour is dull wax yellow. Itis translucent—weathering white and opaque, 
but it readily reabsorbs water and becomes again translucent. It falls to pieces 
in water, with somewhat of a burst, in a manner similar to bole. It is softer 
than the nail, may be cut out of the druses like cheese, and is altogether 
very similar in appearance to common soap. 
1:29 grammes yielded— 
Silica, . t ‘ . 40°329 
Alumina, . : ; eee a 
Ferric Oxide, . } . WUE OF2 
Manganous Oxide, . : 7 TDL 
Temes WirKih Ade atiy “SKB 
Magnesia, : : St .7i 
Water, . : ; . 24°338 
99" 998 
Loses 15 - 132 of the above water at 212°. Insoluble silica, 7 - 83 per cent. 
Among the debris which occurs at the foot of a separate outlying ridge of 
rocks which lies north-east of the Quiraing saponite is found of the following 
colours :—Dark-brown, green, yellow, brown, light-green, and Venetian-red. 
It here is in dense structureless layers, also stalactitic and in minute crystalline 
spheres, but the forms are indistinct. A fine echo may give the name of 
Echoing Craig to this locality. The order of deposition of minerals here is— 
Saponite, chabasite, plynthite, calcite, Thomsonite, chabasite, apophyllite, anal- 
cime, mesolite. 
It has thus to be remarked that while the saponite of the volcanics of Old 
Red Sandstone age has been the substance /ast deposited in the druses, that of 
the volcanics of the Lias and Oolite has been the jirst. 
The inferences to be drawn therefrom will be considered in a future chapter 
on the Zeolites. 
There can be little doubt that the “ prasilite ” of THomson (“ Phil. Mag.,” III. 
Xvii. 416, 1840) is saponite. He describes it is a leek-green mineral, soft as 
Venetian talc, and with gravity = 2°311. Itis stated to contain silica, alumina, 
ferric oxide, magnesia, and about 18 per cent. of water. Its locality also was 
the Kilpatrick hills. 
The marked feature of saponite is the extreme ease with which it loses part | 
of its water when heated, and the speed with which it regains it upon cooling. 
If a quantity of the mineral half-filling a closely-stoppered bottle be placed in 
