NATURAL HISTORY. 
about 50) ; some of the richer specimens are active- 
ly magnetic ; when pulverized, the ore is brownish 
black, and passively magnetic. [t occurs also 
mixed with sulphur and with arsenic, in coarsely 
granular masses. Spathose carbonate of iren and 
also iron-pyrites are met with; the latter, either in 
decompusing granular concretions, radiated, in 
more or Jess perfect cubic crystals, and in small 
spangles disseminated through the coarser granular 
ore. Copper-pyrites and arsenical pyrites also oc< 
cur, the former very sparingly.’’ 
MANGANESE has been worked to some extent at 
Doddiscombesleigh, Hennock, [sington, and Ide- 
ford; the ores are chiefly the black and grey oxides, 
which usually occur in bunches ; after pulverising _ 
and washing, it is put in casks and shipped off in 
this state for the market. Roofing Slate, several 
large and excellent quarries of this are met with, 
the principal are those at Staverton, and Nether- 
ton—they are worked chiefly for the supply of the 
neighbourhood. This formation especially near the 
Ime of junction with the granite, richly deserves to 
be more carefully explored than has hitherto been 
the case ; but practical miners have great local pre- 
judices, and in general, can only be induced to ex- 
tend their operations gradually and carefully from 
points ef established reputation—even in Cornwall 
there is much promising ground yet unexamined, 
Tue Lime-stoneE, This rock is quarried and 
burnt to a great extent, for the purpose of a manure; 
the rocks on the Western-most line, from Haldon 
R 
