Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/285

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30.Derry in Mifflin.
F³. 257
SiO2, 1.580 per cent.
Al2O3, 1.004
Fe2O3, .257
Phos. .016

The furnace of this company was remodeled during the summer of 1888 and shows the following dimensions now: Height, 50′; bosh, 9′; hearth, 5′. There are four tuyers, each 4″, Height of bosh above bottom, 16′, and an output of from 18 to 20 tons a day.

The furnace was built in 1862 and has been largely run upon coal-blast charcoal iron since the time of its erection. Since its alteration it has been put on coke, and the ore charge during the summer of 1888 was a mixture of roasted Townsend carbonate ore, Ferguson valley fossil ores and some mill cinder.

Townsend ore bank.

The Townsend ore bank, from which the largest percentage of the ore supply for this furnace was being obtained during the season of 1888, is situated on the Townsend farm of the Logan I. and S. Co., in the narrow valley on the eastern side of the township between the two Oriskany sand- stone ridges. It is about 4 miles east of Logan.

The ore occurs immediately above Oriskany sandstone, a thin clay seam being the true foot wall; and the clay, by reason of local rolls, occasionally enters in wedge shaped masses into the bottom ore. The hanging wall is a smooth black slate, making a firm roof, so that the timbering in the mine is nowhere very extensive. The scarcity of good lumber, however, makes the little timbering that is done an important item of cost. The ore is a carbonate of iron and, rather sulphurous, the iron pyrites occurring irregularly in thin flat seams through the ore mass rather than in any finely disseminated crystals through the ore lumps. Consequently when roasted (by which about one-half the total percentage of sulphur is eliminated) very little coal is required after the fire is once started, the burning sulphur completing the operation of roasting.

Very little oxidation has taken place in the surface ore as only about 5′ or 6′ of the bed has been altered to oxide