t 
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 505 
1:421 grammes yielded— 
Silica, . A : * 785 
From Alumina, . ‘007 
Sy AS a — 55° 734 
Alumina, . E : ; * 045 
Ferrous Oxide, . - so 203 
Manganots Oxide, . 5 - 008 
Damien ys. 9 2 tee poe ea 
Magnesia, ee Ae erm SES) 
Rotashys ws ‘ : h -138 
Soda, ; : ; ACA 
Water, . 22305 2°438 
100 « 625 
Was perfectly pure. 
Schistose Allomorph. 
5. This still more remarkable variety is similar to the last ; but it is very 
much softer, looser in structure, and more schistose. 
It occurs in the sea-banks at Leegarth, on the east side of Trista Voe, in 
Fetlar. It was apparently considered to be talc-slate by H1spert, and its 
extreme unctuosity gave some countenance to such a view. 
It is white, with a slight tinge of green; it readily breaks into fissile slates, 
the cross fracture of which shows a loose luminated arrangement of particles, 
which, under the lens, appear to be minute granules, with occasionally an 
Obscure fibrous structure. It is so soft as not only to be abraded readily 
by the nail, but also to leave, when handled, a powder of extreme unctuosity 
upon the skin. It can with great ease be crushed into powder. It is asso- 
Ciated with strata of a darker variety of the same substance, which variety 
carries minute crystals of magnetite, and is. slightly actynolitic. Fasciculitic 
asbestus also occurs at this spot. 
The specific gravity of the schistose mineral is 2 * 955. 
VOL. XXVIII. PART IL Gr 
