MINERALOGY, I3I 
cavities which were represented in Fig. 3 on Pl. 6 to show the analcite, 
were all first coated with sphaerosiderite, which often assumed in them 
the most fantastic forms. In the thin sections it is deep yellow in color, 
appears often agate-like in structure, but in polarized light appears to be 
an aggregate of very fine fibres or scales. It is not uncommon to find 
some of this substance in sections of our basic rocks. 
93. RuopvocurositE [Mn CO*]. 
This mineral is found at Winchester. When pure, it has a light rose 
color ; but our mineral is usually blackened by decomposition. It is not 
common, and does not show its crystalline form, which is rhombohedral. 
94. MaracuitEe [Cu? CO* + H’0O]. 
This bright green carbonate of copper, though not found in well crys- 
tallized forms, occurs at Littleton in the slaty rocks, in stellated groups 
of needle-like crystals. In the condition of a green crust it has been 
found in the rocks at Franconia, Hanover, Dalton, and Orford. It is 
associated with sulphurets of copper, and generally results from their 
decomposition. 
95. Azurite [Cu C? O’ + H’0}. 
The blue carbonate of copper is associated with the green at Fran- 
conia. Like the malachite, it is in the condition of a non-crystalline 
earthy crust. 
* * * * * * * * * 
In concluding this chapter, what has been said with reference to the 
localities of minerals may be very conveniently summed up in a cata- 
logue of the towns, and the minerals that, to the knowledge of the sur- 
vey, have been there identified. This catalogue not only embraces those 
mineral occurrences that have been referred to in the preceding pages, 
but also includes many others which in those connections it would have 
been tedious to enumerate, and mention of which is more serviceable 
when placed here. Though many of these minerals have been known 
to exist for a century, still to the field laborers on this survey, with Prof. 
Hitchcock at their head, the people are indebted for a knowledge of a 
large number of these occurrences, 
