112 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
On : 484 grammes— 
Silica, . F ‘ *166 
From Alumina, . * 003 
*169 =e 34°917 
Alumina, . ; 3 ey bles) 
Ferric Oxide, . . = wba felis 
Ferrous Oxide, . : a, 20S 
Manganous Oxide, . : "414° 
Lime, : : ; « 62082, 
Magnesia, . ‘ f yo 264: 
Water, ; f ; 7 768 
99 + 655 
Of the above water 1° 033 was lost at 212°. There were traces of alkalies, 
but there was not enough material to determine them upon. 
The mineral was freely soluble in chlorhydric acid. 
Atoms. 
Silica, . : , 34:°917 1:164 8 36°28 
Alumina, . 7°158 VA) : 7:78 
Ferric Oxide, . 12°713 ‘6a Pas 12°41 
i f 5 : 16°082 c 7:6! 
Lime, ; 6 é 574 i 104 7 17°69 
Magnesia, . : 8:264 +413 46 
Water, . : : eos 1:974 13 17°69 
Formula— 
(Ca: Mgr)’ Si? + 2(Al,, Fe,) Si + 13H,. 
Or ae 
RY Rie SisEa3: 
RUBISLITE. 
This substance I found along with Professor NicoL in a deep pat of the 
quarry of Rubislaw, near Aberdeen. 
It was imbedded along with crystals of muscovite in an exfiltration vein. 
It occurred in a solid lump, and also forming a “corded structure,” pervad- 
ing felspar, identical in appearance with that noted by me in felspar: it thus 
occupied the position of the oligoclase or albite which usually forms that 
structure. 
