Navassa/Report of Augustus H. Frick
SKETCH C.
SURFACE VIEW OF PORTIONS OF A FIELD OF PHOSPHATE.
SKETCH D.
Vertical Sections of Phosphate Embedded in Limestone.
A. PhosphateB. Limestone
REPORT
on the
Phosphatic Mineral of Navassa Island, W. I.
To the Corporation of the Navassa Phosphate Co.
Sirs:
The undersigned sailed for the Island of Navassa in June last to make a minute examination of its geological formation with especial relation to the mineral phosphates found on it, and has now the pleasure of making the following report:
Geographical Position and Features of the Island.
Navassa is situated in latitude 18° 25′ north, and 75° 5′ west of Greenwich, between the islands of Hayti on the east and Jamaica on the west, in the channel called the "Windward Passage," and distant from New York 1,300 miles.
It is 41/2 miles in length from N. E. to S. W., and its greatest width 21/2 miles. The north end being the narrowest point it presents the shape of a pear. It has two levels or flats—a lower one rising from 12 to 80 feet above the sea, and an upper one of 300 feet above it. The former begins about a half a mile west of the northern end, and widening more and more towards Lulu Bay, S. W., becomes beyond that point almost a perfectly level plain, covering, at a fair estimate, an area of 2,000 acres. This plain stretches around the south end, and continues on for more than a mile on the northeast side, until it is cut off by barren white limestone rocks. Near (south) Lulu Bay, a limestone reef traverses the lower flat, thus dividing it in two, The more southern one contains by far the greatest number of acres.
The upper flat is divided by reefs, or rather elevated limestone strata, (resembling, on account of their sharp pointed and perforated structure, coral reefs,) into several level fields, as can be seen by the Map B, representing the surface of the island. It covers 1,000 acres, of which about forty have been worked, yielding from forty to forty-five thousand tons of phosphate of lime.
The water close to the shore is very bold, twelve fathoms deep, excepting a point near the western extremity, where a coral reef shoots out to the westward about one hundred and fifty feet, on which the depth of water is but twenty-seven feet, with fifteen fathoms all around it. The greater part of Navassa is densely wooded by palm trees and shrubbery common to the tropics. Large flocks of sea birds of various kinds roost on the trees of the lower part of the island, but their excrements are hardly perceptible. The climate is perfectly healthy; sea breezes moderate the tropical heat, so that even white labor can be employed without injury to health.
The only unfavorable feature of Navassa is the entire absence of springs. All the water necessary is either obtained from rains saved in cisterns, or has to be obtained from the near islands or the States.
Geological Formation.
The great progress made of late years in the science of geology, has made us so well acquainted with all the rock formations, that it is now a comparatively easy matter to determine and classify the different strata and place them where they belong.
Among the many petrified shells covering the joints of the limestone, the best preserved are Pecten Personatus, (the inner side of them,) Gryphaea Virgula and Ammonites Striatulus, in every respect like those so frequently met with in the Jura system of Europe. The limestone of Navassa belongs therefore to the secondary formation. It is of white color, has an uneven, rough fracture, enclosing some round grains (oolites) and apparently a great many small shells that cannot now be classed.
This island was, at the time of its origin, under the level of the sea, where the stratas were successively deposed in a more or less horizontal position. After a stratum of the compact limestone had been formed, layers of phosphate of alumina, phosphate of lime and globular lime, alternately changing with another, settled on it, being followed again by a stratum of the former. This process has no doubt been going on for many ages, as the great number of strata of which the Island is composed demonstrate—as they stand now quite perpendicular, it is further evident that they were afterwards upheaved by plutonic power. Their strike is S. to N., possessing a thickness that varies very much. The strangest appearance in the white limestone are the round holes, from 1/2 of an inch to 6 and 8 inches in diameter, produced probably from the emanation of gases. The sides of these holes, as well as those of the phosphatic beds, are covered with a crust of pure phosphate of lime, reaching a thickness of over half an inch.
The rocky kind of phosphate contains a few grains of yellow and blackish sand, but no remains of fossils of any kind are perceptible, having doubtless been destroyed by the action of the heat that existed at the time of the upheaval.
On the outcroppings of the limestone strata, the phosphatic minerals appear in nests of very irregular forms and sizes, as shown by sketch C. The greater part of them widen considerably in descending, and are finally cut out. See sketch D. I am, however, of opinion that, by removing the limestone intervening, similar nests will be found underneath, as it must be taken for a certainty, that the phosphate of lime running parallel with the strata of the carbonate of lime, will extend as far as the latter, a presumption partly proved, at a point right close to the level of the sea, on the N. W. side of the island, where the surf has washed away a part of the limestone and exposed a large stratum of rich phosphate, at a distance of over 250 feet from the top of the island.
On the lower flat the greyish phosphate is predominant; on the upper one the reddish brown. At innumerable places the hard undecomposed phosphate of lime crops out, from which, as well as from the fine, samples have been taken indiscriminately by Doctor Liebig, for the purpose of obtaining perfect and correct average ones.
Working of the Phosphatic Deposits.
The working of the phosphate of lime since its commencement, about nine years ago, proves clearly how easily and cheap this mineral can be sent to market. Pick and shovel are the only tools needed. After the upper part, generally mixed with many small roots and fibers to a depth of two or three inches, has been removed, the disintegrated mineral appears. in form of roundish grains, wanting only to be loosened somewhat with the pick to facilitate the shoveling. Most of the openings, as stated already, increase in size, frequently to a considerable extent, a single one yielding many tons of phosphate; a circumstance that makes it very difficult to arrive at an exact estimate of the quantity of the fine phosphate contained in them. The only feasible plan was, therefore, to ascertain what area had been worked near Lulu Bay, on the lower flat. We found that from 11/2 acres, one thousand six hundred and thirty-five tons had been shipped to a house in Camden, N. J., and that there yet remained two large piles at the landing ready for shipment, containing at the lowest estimate five hundred tons, making two thousand one hundred and thirty-five tons, although it had not been worked with that care and economy which the value of it demanded.
The island possesses an area of somewhat over 11 square miles, and deducting from it one-half as occupied by carbonate of lime, it leaves 51/2 square miles which are covered with the phosphate. Taking only 5 miles into consideration, the same, according to the above statement, will yield four million five hundred and fifty-four thousand six hundred and sixty-six tons of the fine variety of phosphate. That this estimate is correct is further proved by the quantity worked out from not quite 40 acres on the upper flat, and from which forty-five thousand tons were obtained, of which about five thousand tons lay near the landing waiting shipment.
Among the fine-grained phosphate is found a great many loose lumps, and in working lower down in most of the nests, this mineral assumes a hard rocky nature.
[ have stated already that the hard phosphate is visible on the surface at a great many places; should it prove by analysis to be good, then it can be said, without the least exaggeration, that this mineral is indeed inexhaustible.
The cost of digging and wheeling a ton of the disintegrated phosphate, I estimate at one dollar. This work can be lessened, and consequently made cheaper, by laying railroad tracks, the construction of which, on account of the level nature of the flats, could be put down at a small cost, especially if the rail is laid on wooden tracks. The two shutes, from which the boats are loaded, will be sufficient for a long series of years: and as pretty near all other accommodations, such as houses for the hands, for storing provisions, for catching rain water in cisterns, are put up, the working capital need not be large.
In conclusion, I wish to remark, that the harbor of Navassa is an ordinary trade wind harbor, but being sheltered by the adjacent mountainous islands of St. Domingo and Cuba from heavy gales and seas, is much improved thereby. There are no reefs or shoals near the island that would make shipping dangerous, and vessels can haul close along side of the cliffs, if they wish to do so, as the depth of water all around the island is twelve fathoms, and the same depth for a mile or more from it, with but little variation. The facilities for loading vessels are therefore very superior. Owing to the cliffs being about forty feet perpendicular, the phosphate can be shuted down in boats and launches. One hundred tons a day are frequently put on board of one vessel with only thirty or forty men and two boats.
Taking into consideration the immense quantity of phosphate deposited on your island, the great ease for digging and loading, the short distance to a market, the giving out of the phosphatic guanoes of the Caribbean sea, the scarcity of it in nature, and the great demand, which will be almost unlimited, for the manufacture of super-phosphate, it cannot fail but that Navassa must become the main source from which this mineral can be supplied.
Wishing you all success,
I remain,
Very respectfully, yours,
AUGUSTUS H. FICK,
Mining Engineer.
BALTIMORE
Printed by J. B. Rose & Co.
5 South Calvert Street.
NAVASSA.