The magnet which attracted the Spaniards at the time of the conquest was the island's mineral wealth, especially the gold deposits. It is a historical fact that large quantities of gold in dust and nuggets were collected during the first years of Spanish colonization. According to the Spanish writers, from 1502 to 1530 placer gold was produced to the value of from $200,000 to $1,000,000 per annum. The fleet which set out in 1502 and was wrecked by a hurricane before leaving the coast waters of Santo Domingo was laden with gold mined in the island. A tribute of a small amount of gold each year was imposed on half the Indians of the country. Much of the gold came from the mountains behind Santiago and La Vega, from the gold-bearing sands of the Jaina River, around Buenaventura, and from the vicinity of Cotui, then called "Las Minas." Ancient pits are still to be found in all these places. At La Vega a mint was established for coining gold and silver. A nugget of extraordinary size was found by an Indian woman in a brook near the Jaina River; her Spanish masters in their exultation had a roast suckling pig served on it, boasting that never had the king of Spain dined from so valuable a table. The Indian received no part of the gold: "she was lucky if they gave her a piece of the pig," remarks Father Las Casas. This nugget was purchased by Bobadilla to send to Spain, and went down with the 1502 treasure fleet.
The gold deposits found by the Spaniards were the surface accumulations of centuries. When these were exhausted and the supply of cheap labor fell off owing to the dying out of the Indians, the mineral production waned. In 1502 labor difficulties caused a temporary cessation in mining. In 1511 many mines were definitely closed because of the scarcity of laborers and because the cultivation of sugar-cane offered surer profits. Then came the discovery of mines of fabulous wealth in Mexico and Peru, and the interest they aroused, as well as the lack of labor in Santo Domingo, caused the mines of the island to be completely neglected. Finally, in 1543, mining work ceased and by a royal decree all mines were ordered closed. Prospecting and desultory mining, especially placer mining, have been kept up, however, until the present day.
The prospecting has generally been confined to the more accessible regions and nothing is known of the mountain valleys in the interior. The mineral deposits discovered have been of sufficient richness to cause the formation of mining companies for their development or further investigation. I do not, however, know of a single case where prospectors or mining companies have ever made expenses. The cause of failure has most frequently been the lack of transportation facilities in the island, on account of which the cost of carrying the ore to a place where it might be reduced became prohibitive. Sometimes enterprises failed because the deposit turned out to be too small, sometimes because the ore did not keep up to the standard, and not infrequently mining companies fell by the wayside because of bad management. Enough evidence of mineral wealth has been found to justify the belief that workable deposits do exist, and to warrant careful further investigation, especially as the means of communication are extended.
The metals most frequently found are gold, copper and iron. Veins of auriferous quartz are found throughout the central chain, the richest lodes being encountered in metamorphic rocks near crystalline formations. The metal is most abundant in placers formed in the river beds. Such placers are common in the Jaina River and its tributaries in the province of Santo Domingo; in Bonao creek in Seibo province; and in the Verde River, the streams of Sabaneta and a number of other streams of the Cibao. On the upper Jaina and on the Verde River there are still persons who make their living by washing gold from the river sands. Hydraulic mining was attempted in Santiago province, but after the construction of an expensive canal the project was abandoned. Under the liberal mining law mining privileges have in recent years been granted for gold mines reported at numerous places in the communes of San Jose de las Matas, San Cristobal, Janico, San Juan de la Maguana, Sabaneta and others. Prof. William P. Black, one of the scientists accompanying the United States Commission of Inquiry in 1871, reported:
"There is a very considerable extent of gold-bearing country in the interior and gold is washed from the rivers at various points. It is found along the Jaina, upon the Verde, and upon the Yaque and its tributaries, and doubtless upon the large rivers of the interior. Some portions of the gold fields were worked anciently by the Spaniards and Indians. There are doubtless many gold deposits, not only along the bed of rivers, but on the hills, which have never been worked, and there probably is considerable gold remaining among the old workings. The appearance of the soil and rocks is such as to justify the labor and expense of carefully prospecting the gold region."
Copper is next to gold in frequency of occurrence. Some of the best deposits have been found in the commune of San Cristobal, province of Santo Domingo. A company working lodes at Mount Mateo on the Nigua River, encountered ore yielding as high as 33 per cent of copper. On the Jaina River near the ruins of Buenaventura, I have seen promising ledges of copper ore. Copper carbonates predominated, the green ore known as malachite and the beautiful blue ore azurite were quite common, and white quartz, which on being broken showed little specks of native copper, was also to be found. The asperity of the region, the absence of roads and the uncertainty as to the extent of these deposits caused the attempts at working them to be but feeble until recently, when extensive works of development were undertaken in the vicinity. Copper veins have also been reported in the mountains of the commune of Bani, province of Santo Domingo; in the communes of Cotui and Bonao, province of La Vega; in the canton of Moncion, province of Monte Cristi; in the commune of San Juan de la Maguana, province of Azua, and at a number of other places.
Iron is reported in large quantities in various parts of the country. The largest deposit so far known is on the banks of the Maimon River in the municipality of Cotui, being a bed of black magnetic oxide of iron, nine miles long. It is said to be excellent in quality and inexhaustible in quantity. The difficulties of transportation in this case could be obviated by the canalization of the river to its confluence with the Yuna River, so as to make it navigable for small boats. Iron ore has been discovered on the slope of Mt. Isabel de Torres behind the city of Puerto Plata, limonite deposits at various places in Santo Domingo province, and a rich black iron oxide on the upper Ozama River. A layer of iron pyrites extending from Los Llanos all the way to Sabana la Mar was believed by its discoverers to be a gold mine. The central ridge of Santo Domingo is part of the same mountain chain which extends through Santiago province in Cuba where enormous quantities of iron are produced, and it is not improbable that some of the Dominican mines will be found to pay.
Coal mines found in the Samana peninsula produced a kind of lignite which proved of little commercial value and gave rise to the belief that the Republic's coal deposits had not emerged from the formative period. Later investigations show that while there is considerable undeveloped lignite, coal suitable for fuel is not wanting. Small coal deposits have been discovered in the Cibao Valley, between the central and the northern mountain chain, in the province of Pacificador and that of Santiago. Anthracite coal found at Tamboril, near the city of Santiago, was used to run a small motor exhibited at an industrial fair in Santiago in 1903. In the commune of Altamira, province of Puerto Plata, lignite and anthracite beds have been discovered, and traces of anthracite have also been found in San Cristobal commune, and in the petroleum region of Azua. In the central mountain chain a valuable coal deposit has been found on the Haitian side and similar beds may be expected in Santo Domingo.
Silver has been discovered at Tanci, near Yásica, in the commune of Puerto Plata. The old chronicles refer to silver mines at Jarabacoa and Cotui in La Vega province, also to others near Santiago, near Higuey and on the Jaina River. Platinum occurs at Jarabacoa, traces of quicksilver have been found near Santiago, Banica and San Cristobal, and tin in Seibo and Higuey.
Rock salt is found near Neiba in inexhaustible quantities, there being several hills of native salt covered with a thin layer of soil. The fact that the waters of Lake Enriquillo are saltier than the sea is attributed by some to a deposit of this kind. The salt is so pure that it does not attract moisture and deliquesce. The isolation of the district has been an obstacle to the development of the salt mines, but there is a project for the building of a railroad to the port of Barahona. Part of the salt used in the island comes from salt ponds near Azua, where salt is obtained from sea water by solar evaporation.