120 



constitute It an important ore of iron, with us It occurs chiefly, 

 perhaps almost exclusively, in the form of granules disseminated 

 throughout the mass of many of our igneous rocks. 



In Vol. ii. p. 565 of the Geological Magazine, I called attention 

 to the occurrence of a mineral new to the British list in the 

 Hjematite mines of West Cumberland. This is Hausmannite, 

 the tetragonal form of Manganese Protoxide and Sesquioxide ; or, 

 according to some, Manganese Deutoxide. 



Since the notice appeared, Mr. Kendall informs me that 

 considerable quantities of the ore have been found. 



An ore of considerable commercial importance, when found in 

 large quantities, is Pyrolusite, Manganese Bin-Oxide, which 

 differs from Hausmannite in crystallizing in the Rhombic instead 

 of in the Tetragonal system. This ore of manganese is very 

 generally diffused throughout our district, but nowhere occurs in 

 workable quantities. It is found in greater or lesser abundance in 

 association with most veins of iron, and is also found along with 

 the lead and copper ores of the Caldbeck Fells. One very 

 common form of the mineral is that of the singular dendritic, or 

 moss-like aggregations that occur on the divisional planes of many 

 of our harder rocks, especially on the Penrith Sandstone. A very 

 beautiful example of this kind was presented to the Carlisle 

 Museum by my colleague Mr. Colvin, and others exist in most 

 collections, where they are not unfrequently regarded as examples 

 of fossil plants. 



This ore is much used in the preparation of oxygen for various 

 purposes, and the beautiful amethystine tint it imparts to glass 

 is turned to account in neutralizing the objectionable bottle-green 

 tint resulting from the ferruginous impurities occurring in the 

 materials employed in glass manufacture. 



Like the ores of iron, this ore of Manganese seems to have its 

 origin connected in some way or another with the deposition of 

 our Red Rocks. 



