PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 457 
assumed the characters of a statuary marble, though it is much too close- 
grained and dense to be regarded as possessed of beauty. It also, like the 
Skye marble, either has naturally, or rapidly assumes, a greasy opacity, which 
quite unfits it for the purposes of the sculptor, or even for domestic architecture. 
Of the yellow serpentinous marble which is associated with it, quite a different 
account must be given. It unquestionably is the most beautiful true marble in 
Scotland. It may be doubted if any more striking ornamental stone can be 
seen than that of which the mantel-pieces in the hotel at Blair-Athol are 
_ constructed. 
| The white marble occurs at various points in the glen, being well exposed in 
| the bed of the stream. 
At a few hundred yards above the Forest Lodge a bed crosses the stream. 
Formerly it here formed a fine natural arch ;—a quarry having been opened at 
Se  —————eee eee 
q 
: 
| the spot, this has long since given way. Here the lime overlies a stratum of a 
dark, probably Biotitic slate. This has been regarded by some geologists as 
an igneous rock. 
| The marble of this quarry, during the time when it was wrought, yielded 
specimens of tremolite of very remarkable beauty ; but the malacolite, of more 
| subdued appearance, was hardly noted. It is found in a belt or band, being 
- yery similar in its mode of occurrence to that at Shinness, though it has more 
| of a foliaceous massive, and less of a crystalline character. Milk-white, and 
'\a very pale green are the tints it here assumes. Its associates are yellow 
| serpentine in patches, and radiated greenish-grey tremolite. 
| Margarodite in small crystals, simulating talc, disposed with a parallel 
_jarrangement in the marble, is also to be occasionally found. The rock then 
assumes more or less of a schistose structure. 
The white malacolite has a specific gravity of 3:124; the greenish, of 
3°1625. That with the faint green tint was analysed. 1°495 grammes 
 yielded— 
‘ 
| Silica, 5 : . 53° 244 
| Ferrous Oxide, ea rE 
| Manganous Oxide, . 21128} 
| Lime, : , : 4 BROT. 
| Magnesia, ; ; 7) 18862 
99 * 889 
| Water, . : : Paes LOWE 
| 
| 
4 per cent. of the silica insoluble ; possible impurity unknown. 
| Dr Maccuttocu mentions the occurrence in this quarry of a quartz with an 
janusually high gravity. A thin layer of a fine granular quartz, very dense in 
tructure, overlies the malacolite, but its specific gravity was found to be 2°645. 
VOL. XXVIII. PART It. 6c 
