[Assembly 
My acknowledgments are due to the Messrs. Garbutt, and to the 
Messrs. McVean, for valuable information, and for interest manifested 
in the progress of the survey. 
Mdals. 
Iron is the only ore of any importance in this county, blende and 
galena, (or the sulphurets of lead and zinc) are found in the bituminous 
limestone, but never in large quantities. The argillaceous iron ore al- 
ready noticed, extends from the Genesee river to the eastern limits of 
the county, but has not yet been examined in any part of this distance. 
In Wayne county, a few miles east of Monroe, it is three feet thick, 
and it would probably be found about the same thickness in Penfield. 
Bog ore is found in many places, but no where in sufficient quanti- 
ties for making iron. The deposites of this ore in Monroe county 
never attain a thickness of more than a few inches, and are of limited 
extent. In some places this ore is mixed with clay, producing yellow 
ochre. 
QuickTime and Hydraulic Cement. 
Quick-lime is manufactured in considerable quantities from the bitu- 
minous limestone. There are several kilns near Rochester, and others 
farther west and south. East of Rochester lime is made from boulders 
and fragments of limestone on the surface and embedded in the soil. 
This limestone contains magnesian earth, and some other impurities, 
rendering the lime less valuable than otherwise it would be. In some 
localities certain strata only are used for making lime, and in other 
places the whole of the rock is too impure for that purpose. This is 
owing to the predominance of siliceous and aluminous matter. 
Hydraulic Cemerd, 
As this material is extensively used along the line of the Erie canal, 
it may be proper to offer some remarks on the quality and situation of 
the substance used for this purpose. Nearly all the hydraulic cement 
now used is brought from Onondaga. 
I have already remarked, that there is no formation to which the term 
hydraulic limestone is exclusively applicable. The upper part of the 
calcareous shale as it graduates into the bituminous limestone becomes, 
by admixture of siliceous matter, a substance considered fit for hydrau- 
lic cement. The upper portions of the gypseous rocks, by similar ad- 
mixture, becomes a silico-aluminous limestone, used for the same pur- 
pose. 
