LIME. 
237 
St. Lawrence County. Coralloidal arragonite is credited by Dr. Emmons to the Parish 
iron ore bed in the town of Rossie. Although this situation is favourable to the occurrence 
of this mineral, all the specimens which I have seen, and they are quite numerous, belong to 
the preceding species. 
GYPSUM. 
[Gypse is said to have been the ancient name of calcined sulphate of lime.] 
Chaux Sulfatee. Hauy. — Sulphate of Lime. Cleaveland. — Hydrous Sulphate of Lime. Thomson. — Prisma- 
toidal Gypsum, or Common Gypsum. Jameson. — Prismatoidisches Gyps-Haloid. Molis. — Gypse. Bcudant. 
— Gypsum. Phillips , Shepard and Dana. 
Description. Colour snow-white when pure, but it is often 
also yellow, red, blue, grey, green, brown and even black. It 
occurs regularly crystallized; also foliated, fibrous, granular 
and compact. The primary form is a right oblique angled 
prism. Fig. 102. M on T 113° 8 / . Cleavage highly perfect 
parallel with P, imperfect parallel with M and T. Fracture 
splintery. Lustre of the lateral faces of the prism, vitreous; 
that of the base, pearly. Varies from transparent to translucent on the edges. Flardness from 
1.5 to 2.0; maybe scratched by the nail. Specific gravity from 2.20 to 2.40. Before the 
blowpipe it exfoliates and melts, but with difficulty, into a white enamel. At a lower heat, 
the water which it contains is driven off, and it becomes friable. If then reduced to powder 
and mixed with water, the powder becomes warm, and soon hardens into a solid mass. 
This mineral may be distinguished by its inferior hardness, and by its not effervescing in 
acids, from the carbonate of lime, which it sometimes closely resembles. The powder of 
fluor spar is decomposed by sulphuric acid, with the evolution of the hydrofluoric acid. 
Varieties. The transparent and highly crystallized varieties are called Selenite; those 
disposed in fibrous concretions, Fibrous Gypsum; those which have a splintery fracture, 
Compact Gypsum or Alabaster. Some varieties, composed of fine scaly or dusty and slightly 
cohering particles, are named Earthy Gypsum , a term which is also applied to the impure 
kinds used in agriculture. 
Composition. Sulphuric acid.46.00, lime 33.00, water 21.00. Formula Ca0.S0 3 + 2Aq. 
LOCALITIES. 
In a former part of this work (page 62), I have noticed in detail the most important loca¬ 
lities of this mineral, with reference to its use in agriculture and the arts. I shall therefore 
only introduce here those notices which are interesting in a mineralogical point of view. 
Albany County. Specimens of snowy gypsum have been found in the Helderberg moun¬ 
tains ; and in the town of Coeymans, it occurs in an alluvial bed twenty or thirty feet in thick¬ 
ness, forming efflorescences on the sides of excavations made for roads, etc. 
Fig. 102. 
