248 Sherzer—LNative Sulphur wm Michigan. 
readily removed. Some of the smaller cavities contain noth- 
ing but sulphur and one was found filled with selenite erystals. 
About an acre of this bed had been removed when the locality 
was visited and from this the superintendent estimated that 
one hundred barrels of pure sulphur had been obtained. 
It becomes a matter of interest to speculate upon the source 
of the mineral, since sulphur is so commonly associated with 
voleanic phenomena. At Grand Rapids it has, without doubt, 
resulted from the decomposition of the calcium sulphate, but 
no deposits of gypsum are known in this part of the state. 
That it was brought to the place of deposition in some form 
by water, along with the celestite and calcite, admits of no 
doubt. Although the overlying limestone contains a few 
cavities, but few of them contain any of the sulphur, and these 
are situated very near the sulphur bed. The underlying rock 
is still more free from the mineral, so it seems that the water 
must have been introduced from the side. At one end a 
stream of water was found entering the quarry at the level of 
this bed, highly charged with hydrogen sulphide and deposit- 
ing a considerable quantity of the white precipitate of sulphur 
over the rocks and weeds. Some distance from where the 
water enters, this precipitate begins to assume a slightly yellow 
tinge, and upon breaking open the larger masses a nucleus of 
erystalline sulphur may occasionally be detected. Similar 
masses were found in some of the cavities, the outer portion 
having a lightish-yellow, mealy appearance, while the interior 
is solidly crystalline. The well water of the entire region is 
said to be charged with this same gas and it seems highly 
probable that the sulphur has resulted from its decomposition. 
Not unfrequently masses of the sulphur are found, however, 
of which the outer surface is vesicular, as though corroded by 
some solvent. Still, not believing that the hydrogen sulphide has 
been or could be formed directly from the action of the water 
upon the native mineral, it remains to consider its source. In 
many instances this gas is formed from the decomposition of 
iron pyrite, or marcasite, in the rocks, the iron being converted 
into an oxide and the sulphur obtaining its hydrogen from the 
water. No trace of these minerals, however, was detected in 
any of the rocks, although it is possible that they may occur 
in sufficient quantities farther back. The presence of so much 
carbonaceous matter in the bed itself, as well as in the rock 
above and below, indicated by the color and odor, leads me to 
strongly suspect that the gas has resulted from the decay of 
organic remains, animal or vegetable, or both. 
Ypsilanti, Mich., July 12th, 1895. 
