1S35.] 



FARMERS' REGISTER 



145 



fusion of dark red clay, are thrown out of the dig- 

 gings, together with the mineral. 



It was at Mine la Motte I first received satisfac- 

 tory evidence that the broken up mineral I had 

 seen in the diggings had been occasioned by an 

 accidental derangement of the regular structure of 

 metallic veins, and to which I had always attri- 

 buted these appearances. 



The country around presents an extensive table 

 land, almost denuded ol timber, through which a 

 few slight streams run, which are used to wash 

 the soil taken out of the shallow diggings. The 

 whole surface is cut out into pits of various sizes, 

 from four feet diameter to some exceeding twenty 

 feet square, with an equivalent depth. These 

 larger areas have been the result of a discovery 

 gradually made, that the loose fragments near the 

 surface, which were formerly the sole object of the 

 diggings, were connected with mineral imbedded 

 in the solid rock. Hence, large areas have been 

 opened, without much relation to method, some- 

 times to the extent of half an acre, and gunpow- 

 der is employed to blast the metalliferous rock; so 

 that mining in this particular district is become 

 precisely what quarrying is every where else. 

 The history of these diggings, and the manner in 

 which the sulphuret of lead is often lbund, is as 

 follows. The streams washing through the su- 

 perficial gravels sometimes disclose valuable de- 

 posites of the ore. Adventurers follow up these in- 

 dications wherever found, and commence their 

 diggings: when they reach a depth of twelveor fif- 

 teen feet, or as soon as it becomes inconvenient to 

 throw out. the earth, or hoist out the mineral, a 

 new digging is commenced, and again aban- 

 doned lor a new excavation. Frequently the su- 

 perficial soil for about a foot will be red earth, 

 mixed with mammillary quartz, called here "min- 

 eral blossom," and petro-siliceous stones; a de- 

 posite of red clay of a few feet is then generally 

 found, resting upon a bed of gravel ami flinty 

 pebbles, in which the lumps and fragments, in- 

 cluding extremely small pieces of ore, are found. 

 Deposites of this kind do not difler, in any partic- 

 ular of mechanical arrangement, from any gravel 

 deposites I have seen, especially the gravel depos- 

 ites of gold in the southern states, and which are, 

 without exception, the detritus of rocks brought 

 into these superficial beds by aqueous transporta- 

 tion. Beneath these free deposites lies the real 

 metallic formation of the country, consisting of the 

 fetid calcareo-siliceous rock before described, fre- 

 quently so much decomposed as to admit of being 

 shovelled out, and traversed by horizontal bands 

 of bright galena, or sulphuret of lead, sometimes 

 one inch thick, and frequently a foot thick. In 

 other situations, the ore is very much dissemina- 

 ted in the rock, although always confined in a 

 vein or bandlike breadth, of different dimensions. 

 Where the ore is much disseminated, and the 

 rock is speckled with metallic particles for a great 

 breadth, the ore is usually less productive, yield- 

 ing about forty or fifty per cent, of lead, when the 

 compact mineral in other situations yields sixty- 

 five per cent. Upon such occasions it appears to 

 contain an excess of sulphur. In some instances, 

 I observed broad veins with a considerable dip. 

 but generally the bands of ore were nearly hori- 

 zontal. This locality appears to furnish a full ex- 

 planation of the singular manner in which the ore 

 and sulphateof bar) -tea, in which it is often shealh- 



Vol. Ill— 19 



ed, have come into that free and broken situation 

 in which they are found in the superficial depo- 

 sites. 1 observed veins at the top of the metalli- 

 ferous formation, and beneath the superficial de- 

 posites, in quarries fifty feet across, and twenty feet 

 deep, containing fragments of ore of various sizes, 

 bright and sharp, with the vein, as well as that 

 part of the rock through which it passed, much 

 shattered and dislocated, the back of the vein 

 being broken in numerous places, and the contents 

 exhibiting strong marks of sudden violence. Some- 

 times the galena was rent in shivers, sometimes 

 its horizontal sheet was broken up, and parts of 

 the bright ore, ten inches wide, left standing on 

 their edges, some in one direction, some in another, 

 and the remainder left flat in its old place. In 

 some places the phenomena resemble those pre- 

 sented in the chalk cliffs near the Isle of Wight, 

 in England, where the beds are upset, and the 

 seams and nodules of flint shivered. This is not 

 the case, however, with all the veins. In va- 

 rious quarters at Mine la Motte, especially those 

 which go by the name of lYline la Prairie, where 

 more than half an acre of ground has been unco- 

 vered to a depth of twenty feet, the sulphuret of 

 lead is not only seen running horizontally in hard 

 compact veins in the calcareo-siliceous rock, but 

 is sometimes disseminated for a great extent, in 

 specks through the rock, affording to the eye suf- 

 ficient proof that the stony and metallic matter 

 was deposited at the same time; for if either of 

 them were abstracted, no principle of adhesion 

 would be left for the remaining mineral: occasion- 

 ally the rock changes its character, becoming 

 either calcareous or siliceous altogether, and, in- 

 deed, the structure differs so much as to be some- 

 times hard, sometimes soft, sometimes granular, 

 sometimes compact. Sometimes a bed of sand- 

 stone, three feet thick will lie upon a seam of bright 

 mineral six inches or a foot thick, though more 

 generally it is much thinner, and lies in a flat 

 plate. I have however, seen it in veins of two 

 feet thick. The deepest digging or quarrying I 

 observed at this place did not exceed twenty- 

 five feet; they had not yet begun a regular system 

 of sinking shafts and cutting out drifts, but no 

 doubt this will soon be done, as both the public 

 and private lands around the whole region of 

 Mine la Motte are, in my estimation, underlaid by 

 rich veins of galena, that descend very deep to- 

 wards the central parts of the earth. The su- 

 perficial indications of this mineral are unerring. 



On the approach to a mineral district, numerous 

 localities present a confused, but distinct and 

 rather unvarying character of crystallization. Im- 

 perfect nodules of siliceous matter, masses of 

 mammillary quartz, the crystals of which are often 

 superinduced upon chalcedonized concentric lay- 

 ers with an agate structure, indications of sulphate of 

 barytes, with small fragments of sulphuret of lead 

 in the rain furrows, betray the metalliferous rocks: 

 these are the situations which are chosen to com- 

 mence new diggings in, and with invariable suc- 

 cess as far as respects the finding ore. But from 

 some works which have been recently constructed, 

 and which I had an excellent opportunity of ex- 

 amining, I am confident a thorough reform in the 

 whole system of mining in that interesting coun- 

 try is about to take place, and that it will hence- 

 forward be conducted upon acknowledged princi- 

 ples, consistent with the true nature of metalliferous 



