OF PYRITES AND GYPSUM.
327
historian of Cornwall, though of course with scarcely any know-
ledge of chemical geology, was acute enough to see this, for he
remarks : "There is good reason to believe that mundics are
perpetually forming," and then, after giving instances, he goes on
to observe that "The mineral principles are always active and
forming new concretions."
It was seen, in an earlier part of this address, that gypsum is
often formed by the reaction of decomposed pyrites on calcareous
matter ; it is now seen that, conversely, pyrites may be formed
from the reaction of decomposed gypsum on ferruginous
solutions. Nothing surely can better illustrate the intimate
relationship between these two minerals, or explain why they are
often found associated in the clays of Essex.
Allow me, in conclusion, to congratulate the Essex Field
Club on the attention which is at present being given to the
arrangement of the mineralogical collection in its Museum at
Stratford. My friend, Mr. T. W. Reader, is good enough to
sacrifice much time in co-operating with Mr. W. Cole in over-
hauling this department of the museum. Let us hope that
before the revolving year brings round another Annual Meeting
we shall see, as a result of Mr. Reader's valuable labours, all our
specimens of minerals and rocks not only accurately determined
and scientifically classified, but well displayed and neatly labelled
in the cases of our Museum. It is true that from what we have
seen this evening we can hardly expect the local minerals to
make a brave show, and in order to gain a comprehensive view
of the natural history of the mineral kingdom it is necessary to
travel outside our county. The mineral collection of this Insti-
tution is therefore a general collection ; and when properly
exhibited it will be found to include some of the most beautiful,
the most instructive, and the most marvellous objects in the
whole realm of Natural History.
Note referred to on page 310.—Dr. Philemon Holland the translator of
Pliny, was an Essex man, having been born at Chelmsford in 1552. His
industry in translating the classics led to his being styled "translator general of
his age." Pope refers to the "groaning shelves" weighed down by his ponder-
ous folios.