Vermont farmer. [volume] (Newport, Orleans County, Vt.) 1870-1877, 1871-12-16
Correspondence.
THE EFFECTS OF IRON PYRITEs IN
THE SOIL.
10 The Etiitor ofme Vermont Farmer:

VI tlit illOSl dutl Wlucly uluuStt WIS
on the globe. 1t occurs in rocks of all ages,
usually in cubes simple or modified,
sometimes in dodecahedrons, O2-sjded crys-
tals) and ut other times in octahedrons, g.
sided crystals) disseminated throughout other
rocks 1t is also found massive. The color
is usually bronze-yellow, and the crystals are
often of II bright metallic lustre. 1t Is com
posed of about 1913 per cent. of sulphur and
46.7 per cent. of iron.
The color of this mineral has led persons
ignorant of mincr,llogy to believe that they
were in IA fair way of acquiring II large for
tune upon finding it scattered about in boul-
ders and lodges, hence the name of /" FOOLS
gold" 1t, however, sometimes does contain
gold, and is then termed auriferous pyrites
but it is not of its Importance as n valuable
metal that | would speak.
If those persons who have been disappoint-
ed when appraised of the worthessness of
their supposed precious metal, were acquaint-
ed with the chemical properties of this min
eral and the changes which occur when it is
exposed to the disintcgrating effects of air
and water, they would have consoled them
selves with the reflection that, although it
did not supply them with present wealth, it
was an endowment placed in the safe keeping
of mother earth which would yield compound
interest to their descendants. For, without
doubt, iron pyrites is very important, if not
one of the most important agents engaged in
decomposing the soil and rendering its con-
stituent mineral elements available as plant
food. Before proceeding to discuss the chem
ical changes wrought in the soil by iron py-
rites, allow me to briefly notice what are
some of the more important substances which
go to make up soil or earth as it is usually
found.
The loose,p enetrable material of the surface
of the earth consists of stones, gravel, sand
or clay. The loose stones and pebbles of the
soil are commonly largely silicious, rs these
kinds resist wear most eflectually. Sand is
usually pulverized quartz and schist, often
with some feldspar, mica, hornblende and
other aluminous and magnetism minerals.
Clay is plastic earth, consisting mainly of
pulverized or altered aluminous minerals and
quartz, afforded by the decomposition of field
spar and all argillaceous rocks. Oxyd of
iron, carbonates of lime and magnesia, are
often present in clays.
The constituents of earth vary with the
source from whence they are derived. When
the rock that has afforded the soil is granite
mica slate or the allied rocks, mica, feldspar
and quartz are usually present. Thus a
quartzose rock will furnish silceous gravel
n magnetism will give magnesia to the soil !;
n calcareous, lime trap, the ingredients of
decomposed feldspar or hornblende. Now
what are the general effects of iron pyrites
on these minerals or mineral aggregates as
found in the sOile
The sulphur unites with the oxygen con-
tanned in the air and water and forms sui
phurous acid gas and finally sulphuric acid
This change lberates the iron, in II great
measure, which combines with oxygen from
the same source, and forms protoxyd of iron.
The acid and iron now unite and form II new
soluble compound, the sulphate of iron or
copperas. The sulphurous acid also unites
with the metallic oxyds and form salts called