Page images

The smaller crystals are often transparent at their extremities. It is, however, in color that the corundum of this locality excels. It is gray, green, rose-color, ruby-red, emerald-green, sapphire-blue, and all intermediate shades to colorless. Many pieces of the blue and red have been cut and polished, presenting very good characters as gems, without being of the finest quality.


While this mineral is found so abundantly with the corundum of Chester, Mass., I have not been able to find it associated with these localities. Several specimens of supposed diaspore have been submitted to me, but on close examination it was found to be colorless kyanite.


This mineral abounds in this locality, and, as has been stated, is the gangue-rock of the corundum; it not only surrounds the corundum, but permeates it. There are several varieties, varying in color from a yellowish-green to a dark-green, and differing a little in composition. Two specimens from the same locality were composed as follows:

[blocks in formation]

This curious mica- curious so far as that since my first pointing it out as a characteristic of the emery formation in Asia Minor and the Grecian Archipelago-has been found wherever corundum is, and in the case of Chester emery was the means of leading to its discovery. At the present localities it is abundant and mixed with the rocks and the associate minerals of this locality. Chemical analysis was made of the specimen with the following result:

[blocks in formation]


This mineral occurs in two forms-a black variety and a light-green variety. These minerals have been called by some Arfverdsonite, but neither of them have the composition of that mineral. Their compositions were as follows: Green variety is of a very pale chrome-green, containing and compared with that from Lake Geneva

Light green. Lake Geneva. Black variety.





[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small]

This mineral occurs mostly in a granular form. Its composition is

[blocks in formation]

The other minerals associated with this emery formation are magnetic oxide of iron, chrome iron, rutile, asbestus, talc, actinolite, black tourmaline, chalcedony, anthophyllite, spinel, albite, and picrolite.


The corundum locality that I have described in North Carolina furnishes masses of corundum from which small pieces can be detached, of good blue or of ruby color, perfectly transparent, and nearly free from flaws. When cut and polished they are gems of no mean value. I have not seen the most perfect of them that have been cut, but I have some polished specimens of fine color but with many flaws.

The question naturally arises, what may be the prospects of obtaining the gem from that locality in sufficient quantity to warrant exploration? Up to the present time its occurrence is so different from those in known localities in the East Indies

that we are rather inclined to the opinion that it will only be occasionally that pieces of corundum will be found of sufficient purity and beauty to be of much value as gems; for it is well known that very small defects, if they do not destroy altogether the value of the gem, depreciate its value to a very great extent.

About a year ago a quantity of rolled pebbles were sent to me from the territory of Montana, which upon examination I found to consist principally of corundum; they were like the rolled pebbles from the ruby localities in the East Indies, each one being a little crystal in itself, more or less abraded on the angles, and being of a compact, uniform structure. They were flattened hexagonal prisms with worn edges. They were either colorless or green, varying in shade from a light to a dark-green; some were bluish-green, and there were not any red ones among them; there were some red pebbles, but on examination they proved to be spinel.

These pebbles are found on the Missouri River near its source, about one hundred and sixty miles above Benton; they are obtained from bars on the river, of which there are some four or five within a few miles of each other. In the mining region of this territory on these bars considerable gold is found, being brought down the river and lodged there, and are now being worked for the gold. The stones are found scattered through the gravel (which is about five feet deep), and upon the bed-rock in some of the claims they are abundant and in others scarce. Occasionally they are found in the gravel and upon the bed-rock in the gulches from forty to sixy feet below the surface, but they are very rare in these localities. The greatest quantity of them are found upon the Eldorado bar situated on the Missouri River about sixteen miles from Helena; one man could collect on this bar from one to two pounds per day.

I have had some of the stones cut, and among them one very perfect stone of three and a half carats, and of good green color, almost equal to the best oriental emerald.

My opinion is that this locality is far more reliable to look for the gem variety of corundum than any other in the United States I have yet examined.



This work was commenced in April, 1857, from the bottom of a well that had a depth of twenty feet; the boring tools employed made a hole five inches in diameter to the depth of seventy-six feet from the surface; the boring was now reduced to three inches, and thus continued to the bottom of the well. The depth of well is two thousand and eighty-six feet, flow of water three hundred and thirty-thousand gallons in twenty-four hours, rise above the surface one hundred and seventy feet.

The rock struck, which geologically belongs to the Devonian series, is for thirty-eight feet shell limestone, then for forty feet coralline limestone, at which depth the Upper Silurian is reached. Without being able to make out with any degree of certainty the amount of Upper Silurian passed through, we suppose it to be over twelve hundred feet. At the depth of sixteen hundred feet a sandstone was reached, doubtless of the Lower Silurian, and ninety-seven feet deeper was encountered the first stream of water which reached the surface. This flowed out abundantly and with much force. The quantity not being sufficient, the boring was continued. After this it was unnecessary to use the bucket to take out the material detached by the borer, the force of the water bringing up the fragments very readily. The water increased in quantity in going deeper, the increase being more marked at eighteen. hundred and seventy-nine feet, and still more at nineteen hundred feet, where pieces of rock weighing an ounce or two came up with the water. The water increased every ten or twenty feet to the depth of two thousand and thirty-six feet; here a very hard magnesian limestone was encountered six feet in thickness, after which the sandstone re-appeared, and for the next fifty feet there was no increase of water.

The following table exhibits the series of rock as far as it

is possible to make it out by the fine fragments taken out at different depths, beginning at the top:

76 feet-sand and gravel.

100 feet-tolerably pure limestone, with fragments of fossils.

12 feet-soft limestone mixed with clay.

52 feet-tolerably pure limestone mixed with fossils.

5 feet-limestone with ferruginous clay.

81 feet-gray limestone.

157 feet-limestone mixed with clay.

149 feet-tolerably pure limestone with many portions quite white. 13 feet-clay shale with little calcareous matter.

207 feet-limestone with a little blue clay shale.

33 feet-same, little darker and more shale.

Next 94 feet-pure, very white limestone with fossil alternating with very dark limestone, color probably from organic matter, with some dark shale. 26 feet-shaly limestone.

40 feet-very light and hard pure limestone.

1 foot-white clay.

546 feet—gray limestone, alternating hard and soft.

41 feet-sand rock, white.

4 feet-same, very fine and hard, with little limestone. 60 feet-same, with more lime.

72 feet-same, less limestone.

308 feet-same, sandstone with but little lime.

6 feet-magnesian limestone, very hard.

50 feet-sandstone again.

At the urgent request of many citizens of Louisville the boring was now stopped to give a fair test of the medical virtues of the water that was pouring forth at the rate of two hundred and thirty gallons per minute, or about three hundred and thirty thousand gallons in twenty-four hours. The water by its own pressure rises in pipes one hundred and seventy feet above the surface. The boring was accomplished in sixteen months, and the depth reached is two thousand and eighty-six feet. In order to conduct the water to the surface and prevent its passing off into the gravel beds below, a tube five inches in diameter leads from the surface to the rock, a depth of seventysix feet, into which it is driven with a collar of vulcanized gum-elastic around it. No tubing is found necessary for any other part of the boring.

When the size of the bore (three inches in diameter) and its depth are considered, the flow of water from the well is unequaled by any other artesian well yet constructed that flows above the surface; for although the Grenelle well at Paris delivers six hundred thousand gallons in twenty-four hours, it has at the bottom an area six times as great as the Dupont well, and a few hundred feet up seven times as great. A cor

« PreviousContinue »