Pan mt Q qs _ = 
4. - 
—————K———— 
————$_—_——— 
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 461 
The crystals of sahlite appear to be undergoing an incipient change into 
serpentine, being duller and softer than usual. Such a change is, however, not 
borne out by the analysis. They also rarely contained imbedded bunches of 
radiating crystals of dark green lustrous actynolite, which crystals cut across 
the cleavage plains of the sahlite. 
The colour of this sahlite is pale grass-green. 
1° gramme yielded— 
Silica, é F *A87 
From Alumina, . °008 
- 495 = 49°5 
Alumina, . ‘ : .° 12965 
Ferrous Oxide, . : 2 1k °057 
Manganous Oxide, . : "4 
Lime, , : : . 24:08 
Magnesia, . 2 , = LOPS: 
Potash, . : : : * 567 
Soda, : 3 : , “795 
Water, . ; : : * 688 
99 - 862 
The quantity of iron is, when the colour is considered, strikingly large; and 
as the mineral contains actually less magnesia than usual, no serpentinous 
change has here taken place. In fact the whole of this stratum is markedly 
deficient in serpentinous matter ; though in some places, as at Muir and Mid- 
strath, the lime is little more than a granular malacolite, with but little lime 
lodging between the crystals. As the quarries at the two above-mentioned 
localities are somewhat extensively wrought, and the rock bears in the district 
the character of being an excellent binding lime, the writer proceeded to analyse 
it. He was much surprised to find that a fragment placed in acid effervesced for 
an exceedingly brief period, and was, after this treatment, absolutely unchanged 
in form, and only slightly vesicular—showing a granular congeries of minute 
crystals of malacolite, interspersed with still smaller ones of specular iron. 
There being a possibility that calcined malacolite might combine with water 
and “set,” so as to form a mortar, a quantity was treated and tested in such a 
manner, with a totally negative result. The excellence of this lime must there- 
fore be in all respects open to question. 
VOL. XXVIII. PART II. 6D 
