Secondary form. Similar to the form, fig. 189 of Feld- 

 spar ; but having the faces at the extremities of the prism 

 curved, and somewhat indistinct. 



Cleavage, parallel with P, highly perfect ; with M and 

 T less easily obtained. Fracture conchoidal ... uneven. 

 Most of the faces are smooth, though they possess a lustre 

 much inferior to that of the cleavage planes. 



Lustre vitreous. Color pale flesh-red. Streak white. 

 Transparent to translucent. Grows brown and opake from 

 exposure to the weather. 



Brittle. Hardness = 5-5 ... 6-0. Sp. gr. = 3-4 ... 

 3-634. 



Compound Varieties. Massive : composition granular, 

 individuals sometimes large and lamellar, also fine granu- 

 lar, rarely columnar, strongly coherent. Sp. gr. = 3*612, 

 from Longbanshytta ; 3-634, from Siberia. 



1. The supposed new species, Fowlerite, must be included within the 

 Manganese Spar, as the most important properties of these minerals 

 plainly show, although the Manganese Spar had never been observed in 

 distinct crystals, previous to the discovery of the variety, Fowlerite. The 

 substances called Allagite, Corneous Manganese, Photizite, and Rho- 

 donite, are fine granular, or impalpable varieties, of the present species, 

 occasionally mixed with a variable quantity of Spathic Iron. Their col- 



VOL. II. 3 



