MINERALOGY. 39 



agent acts upon the deposits, magnetite is produced, or sulphuretted 

 hydrogen may, under the same circumstances, convert them in part into 

 pyrites. These three minerals are very often associated together in 

 our state. 



The presence of quite a percentage of titanium, in some of the large 

 deposits of hematite, discourages the hope of their utilization. 



Hematite, as an ingredient of the rocks, is recognized by the circum- 

 stance that in quite thin sections it is not opaque, but transmits light of 

 a blood-red color. Sometimes in the older rocks it is seen in very mi- 

 nute hexagonal scales, so thin as to be quite transparent, and of a fine 

 red color. 



26. Menaccanite [(Fe, Ti)^ 0==]. 



This is a very common mineral, and in almost all the localities that 

 have been given for iron ores some of it is to be found. Besides these 

 places, it is found at Littleton, at Wilton in micaceous crystals on quartz, 

 at Orford, and at F'ranconia in noticeable specimens. 



The proportion between the titanium and the iron varies greatly in 

 this mineral. At times, half its weight is titanic oxide; and, again, we 

 have hematites, in which only a small proportion of the iron is replaced 

 by titanium. Thus, the Unity iron ore contains 6.8 per cent., and the 

 Piermont ore contains t^.S per cent, of titanic acid (Jackson). As titanium 

 is such a common ingredient in our ores, any magnetite or hematite ores 

 that are found in the state should be examined for titanium before any 

 estimate is placed on their value or money expended in their extraction, 

 since the presence of this element is very deleterious. 



Titanic iron is well-nigh universally distributed through the rocks of 

 the state, almost every rock analysis that has been made showing some 

 titanium. When the rocks contain magnetic iron, the analyses usu- 

 ally indicate that it is somewhat titanic. The green slates, diorites, etc., 

 that occupy the Connecticut valley, uniformly contain titanic iron. For 

 example: the diorite at Littleton contains 7.53 per cent, of titanic acid, 

 while it contains but 16 per cent, of iron, a part of which belongs to the 

 hornblende ; therefore it is evident that the iron oxide is a highly titanic 

 menaccanite. 



This mineral, as seen with the microscope, in thin sections of a rock 



