' GEOLOGY AND MINERALOGY. 471 
localities are interstratified with beds of white, pink, and greyish crystalline lime. 
stone or marble. A bed of this substance occurs at the village of Bridgewater, or 
Troy, in Elzevir Township ; and others of fine quality lie in Barrie Township, a 
little beyond the limits of the county. Marble is likewise found in the Townships 
of Madoe and Marmora; but white quartz it should be mentioned is sometimes 
mistaken for it. Attempts have even been made by persons ignorant of the 
nature of quartz, to burn that substance into lime. It may not, therefore, be out 
of place to point out the more salient, distinctive characters of the two, as in the 
following table :— p 
Marble. Quartz. 
Dissolves with effervescence in diluted Not attacked in any way by acids 
hydrochloric or nitric acid.* Does not Scratches glass -easily, and does not 
scratch glass, but may be easily seratch- _yield to the knife. 
ed by a knife. 
These Laurentian or gneissoid rocks constitute also the great iron-holding rocks 
of Canada. This metal occurs in Hastings County in the form of the Black 
or Magnetic Iron ore, a compound of the oxide aad the sesqui-oxide of irom 
containing in percentage values, Iron 72.4, Oxygen 27.6. This valuable mine- 
ral forms thick beds, interstratified with the gneiss, in the Townships of 
Madoc and Marmora; but the ore used at the Marmora smelting works, when 
these were in operation, came chiefly from the south shore of Crow or Marmora 
Lake, in the adjoining Township of Belmont. When the ore contains small shining 
specks or particles (Iron Pyrites) of a brass-yellow colour, it should be made up 
into heaps and roasted, and afterwards subjected for some time to the action of the 
atmosphere, before being taken to the furnace.——The masses of ore broken out of 
the rocks and mixed up with the Drift of this locality, are abundant in some places, 
and of excellent quality, the pyrites having become decomposed, or oxidized, by 
long exposure to atmospheric agencies. 
Tn the north part of Elzevir Township, as well as in adjoining townships beyond 
the limits of the county, some of the green or hornblendie beds of gneiss, contain 
numerous garnets in weil-defined twelve-sided crystals, or rhombic dodecahedrons, 
of a brownish-red colour. These, however, are only of value as mineralogical 
specimens, 
The Laurentian rocks described above, occur in highly inclined strata, dipping 
generally (at least along their more southern outcrop,) towards the north-west. 
The succeeding or overlying Silurian strata, on the other hand, lie on the upturned 
edges of the Laurentian rocks, in almost horizontal beds. A good section, exhibit- 
ing these relations, may be seen on the river banks at Marmora village.t 
Although, as a general rule, where Laurentian rocks prevail, the country is not 
favourably adapted for agricultural occupation, many acres of good and fertile 
* Hydrochloric acid is the muriatie acid or spirit of salt of the stores, For testing lime- 
stone rocks it should be diluted with an equal bulk of water, and kept in a small bottle 
provided with a glass stopper. 
+ The reader interested in these details, may consult also a sketch of the stratification 
near the village of Bridgewater, in Elzevir Township, given in a paper by the writer of this 
notice, in the Canadian Journal for January, 1860, | New Series, vol. V.1 
