256 Geology and Mineralogy of Sudisbury. 
and laminated ; crystals obtusely rhombic—somewhat len- 
ticular. c 
* Granular Limestone. See Geological Remarks. aie: 
Calcareous Sinter, occurs in a ‘stalactical form, under 
limestone rocks. 
Calcareous Tufa. At the falls of the Hooestennuc, te 
bank for some distance below appears to be principally. 
composed of calcareous ‘Tufa. ‘The rocks above and adja- 
cent are lime, which accounts sufficiently for.its formation. 
The surface is very compact and hard, and the solidity 
diminishes in proportion to its distance from the surface. 
In seme places its consistency is that of paste, remaining 
in the same state in which it was deposited. It is celiular, 
and contains sand and fluviatile shells—color yellowish 
white. . 
Calcareous Incrustations are common. 
Magnestan Carbonate of Lime, abundant,—alternates, 
or rather is mingled with granular limestone. 
Bitter Spar—occurs in beautiful rhombic crystals. 
Dolomite—very abtndant, sometimes compact, general- 
ly friable, phosphoresceni—flexible. 
Fetid Carbonate of Lime—occurs in plates, rhombs, &c. 
abundant. 
Sulphate of Alumine—very abundant in yellowish white 
concretions, and efflorescing on mica-slate. Often very 
pure, and by lixiviation might be extracted in considerable 
uantity. ‘The mica-slate is extensively impregnated with 
it, which renders its texture loose and friable, and subject 
to decomposition. It is used by the inhabitants in dying, 
and for other demestic purposes. 
Quartz. 
Common Quariz—extensively disseminated, crystallized 
and massive. 
Limpid Quartz—in six sided prisms, of a considerable 
size ; occurs in alluvial soil, sometimes in geodes in com- 
mon “quartz. 
* Pulverized limestone has lately been tried in this town as a substitute 
for gypsum. From this experiment it seems to answer nearly the same 
purpose. 
