406 



DESCRIPTIVE MINERALOGY. 



ORDER 11. MANGANESE. 



The following species occur in New-York, viz : 



1. Oxide of Manganese. 2. Manganese Spar. 



3. Babingtonite. 



OXIDE OF MANGANESE. 



I have already noticed the principal localities of the common earthy Oxide of Manganese, 

 or Wad (see page 53). 



A crystalline mineral, which probably is the Grey Oxide of Manganese of Phillips, is 

 found in nests and geodes in the hematitic iron ore at Unionvale in Dutchess county. These 

 masses are made up of very minute crystals of a steel or lead-grey colour, resembling specular 

 iron ore. The crystals are apparently rhombic prisms. They have a high metalhc lustre, 

 and are easily reduced to powder. 



The composition, according to my analysis, is as follows, viz : 



Oxide of manganese, 83.33 



Oxide of iron and alumina, ., 6.16 



Water, 10.00 



Haidinger has remarked that the geodes of brown hematite at Huttenburg in Carinthia are 

 often adorned with crystals of arragonite, of calcareous spar, of prismatic manganese ore, 

 or with silvery flakes of another manganesian mineral whose exact composition has not been 

 ascertained.* So far as it relates to the manganese ore, and the silvery flakes, the same 

 remark is applicable to the hematitic geodes which occur at Unionvale. 



MANGANESE SPAR. 



Siliceous Oxide of Manganese. Ckavdand. — Silicate of Manganese. Tlurmson. — Siliciferous Oxide of Man- 

 ganese. Phillips. — Manganese Spar. Shcpard. — Diatomer Augit-Spath. Mol.s. — Rhodonite. Beudant. 



Fig. 480. 



Description. Colour pale rose-red. Streak white. It occurs 

 massive, but the cleavage is apparent in two directions per- 

 pendicular to each other, exhibiting as the primary form a 

 doubly oblique prism. Fig. 480 ; that parallel to P, highly 

 perfect. M on T 121° ; M on P 93° to 94° ; T on P 1 12° 

 30'. Fracture even, or flat conchoidal. Lustre between pearly 

 and resinous. Transparent to translucent. Hardness from 

 5 . 5 to 6 . 0. Specific gravity from 3 . 50 to 3.90. Alone before 

 the blowpipe on charcoal, it becomes dark brown, and melts 



* Brewster's Edinburgh Journal of Science. IX. 332. 



