Gold

Lode and placer gold are found throughout the country. In recent year most, if not all, of the country’s 73 provinces have yielded some gold, whether from authorized or unauthorized operations.

Gold mining the Philippines dated back to the 3rd century A.D., when Chinese traders referred to Luzon as the Isle of Gold. Gold was also mined during the Spanish regime, as recorded in reports of expeditions in the 1570s, a period when extensive placer mining was carried out in various parts of the country.

The early years of the present century saw a surge in local gold production, both from primary (hard-rock) and secondary (alluvial) sources. By 1941, 41 mines were yielding 30 metric tons of gold per annum, a level approximating present-day production.

The collapse of the industry during the Pacific War and recovered only gradually thereafter. By the 1950s gold as a by-product of copper mining began to assume importance and lately has accounted for around half of the country’s gold production. For the past six years, official gold production has been measured at more than 30 metric tons per annum (with a maximum of 35.4 metric tons in 1986).

The principal gold-producing districts are Baguio (northern Luzon), Paracale (southern Luzon), Masbate (Visayas), Surigao (northeastern Mindanao), and Masara (southeastern Mindanao).

Experts have observed that the largest and richest gold deposits tend to lie the vicinity of the Philippine’ fault zone, but there are many exceptions.

Recently, gold exploration has been directed towards epithermal deposits. With the huge volumes of Cenozoic volcanic rocks in the country it is certain that sophisticated exploration techniques will yield considerable additional reserves of gold in the future.

Silver

The Philippines produces around 50 metric tons of silver per annum, entirely as a by-product of gold and copper mining. Like gold, silver is widespread in the country, although the ratio of gold to silver in various deposits exhibits a wide range.

Platinum

Platinum group metals have been detected in ophiolitic (ultramafic) rocks in Zambales, in porphyry copper in Cebu, and with gold in the Paracale gold district. Platinum has been recovered in small quantities together with alluvial gold some localities in the ophiolite belt of Samar island and in Mindanao.

The potential of this group of metals in the Philippines is still unquantified.

Iron and Ferro-alloys

Iron mining dates back to pre Spanish times when the art of smelting was introduced into the country by the Chinese. In modern era, serious mining of iron did not start until 1934 (at Jose Panganiban, Camarines Norte). Several other mines soon followed, but all were closed during the war. Production resumed in 1948 and by 1952 output had reached 1 million metric tons. From 1971 to 1973 over 2.2 million metric tons was produced annually, the highest ever recorded. Thereafter, the industry declined rapidly and production ceased by 1977 when beach sand mining was banned for environmental reasons. Only insignificant quantities have been produced in recent years, mostly as a by-product of other operations.

The principal types of iron deposits in the Philippines are contact-metasomatic, lateritic, and beach (magnetite) sands. Total resources are estimated to be about 4 billion metric tons, but grades are generally low. These reserves, however, may come to assume greater importance as a domestic steel industry develops.

Chromite

Mining of chromite commenced in 1934 in the south of Luzon, followed in 1938 in Coto, Zambales, northern Luzon. The latter proved to be the largest known deposit of refractory chromite in the world.

Chromite was one of the ores who’s production continued during the Japanese occupation. After the war is experienced strong but rather erratic growth, reaching a peak of 850,000 metric tons in 1955. In latter years production has declined to around 200,000 metric tons annually.

Historically, the bulk (85%) of the country’s chromite has been derived from the refractory ores of Zambales, which now contributes around 55% of total production. Deposits of chemical grade chromite are found in eastern Samar, and of metallurgical grade in Dinagat Island, off northeastern Mindanao.

Chromite is hosted by ophiolitic rocks which are widespread in the Philippines. Individual chromite bodies are of various sizes from small pods to several million metric tons. In some weathering and erosion of the host rocks have produced secondary (eluvial, colluvial, or alluvial) accumulations of chromite.

Given the geology of the Philippines, the potential for further discovery of chromite is very good.

Nickel

The vast nickel laterites of Surigao in northeastern Mindanao were first reported in 1912, although these were not exploited until 1975. The first production of nickel in the Philippines was from nickel sulphide, which was found during the course of chromite mining at Acoje, Zambales. Up to 400 metric tons of beneficiated nickel sulphide were produced from 1970 to 1976.

The nickel deposits at Nonoc, Surigao del Norte were mined from 1975 to 1982. The escalating cost of fuel soon posed problems because of the energy intensive recovery process involved. During this period, production of nickel (as metal) ranged from 9,600 to 25,000 metric tons per annum.

Cobalt was an important by-product (up to 1.347 metric tons per annum). This put the Philippines among the world’s 10 biggest producers of both nickel and cobalt.

Negotiations are ongoing for the Nonoc mine and refinery to be re-opened in the near future.

Like chromite, nickel accompanies the ophiolitic rocks of the Philippines. While primary (sulphide) and opethermal (recycled) nickel deposists are known, the bulk of the country’s deposits are of lateritic type, formed by concentration during the processes of tropical weathering.

Manganese

Small deposits of manganese are widespread in the Philippines. Commerical exploitation started in 1940. Annual output has varied widely from less than 1,000 metric tons to 80,000 metric tons. Production in the past decade, however, has been at very low levels, rising to 2,240 metric tons in 1988 and 3,000 metric tons in 1989. The principal mining areas have been southeastern Bohol (Anda Peninsula). Northeast Palawan (Busuanga Island), Siquijor Island and Western Samar.

Deposits are classified as primary and secondary. The former appear to be volcanogenic and marine in origin and of very limited extent. On weathering, the manganese form such deposits sometimes concentrates into extensive secondary layers (Up to 25 meters thick) with grade of 40% to 50% manganese. This later type has supported the main mining operations.

Non-ferrous Metals

Copper

Mining of copper in the Philippines also has a long history although until the second half of this century it was inferior to gold in value.

Crudely-smelted copper was traded with the Chinese in the 14th Century. Late in the Spanish era copper mines were opened at Carawisan (in Panay) in 1842 and at Mankayan (northern Luzon) in 1864.

The metal began to pay a major role in the country’s mining industry, however, only when the potential of large-scale, disseminated (porphyry) copper deposits began to realized. The first porphyry mine (that of Atlas in Cebu) was opened in 1955 and the following year Philippine copper production surpassed gold in value. Except for 1958, copper remained the most valuable mining product in the country until 1985.

Deposits of vein, contact metasomatic. Cyprus, Kuroko and Beshi type are also of economic significance.

In 1974, there were 18 copper mines in operation, most of them of porphyry-type. Production peaked at 304,500 metric tons of copper in metal in 1980, but declined markedly beginning 1982. For the past several years, annual production has averaged around 200,000 metric tons. Constituting 35% of the country’s mine production by value. As mentioned earlier, gold and silver are important by-product of copper mining.

Lead and Zinc

Deposits of lead and zinc are widespread in the mobile belt, particularly in the vicinity of the Philippine fault system. These metals occur in a variety of deposits types – Besshi, Cyprus, Kuroko, contact-metasomatic and vein-type. Lead and zinc have often been recorded in association with copper and gold mineralization, particularly in gold-bearing veins, for instance, in Thanksgiving Mines Benguet and Paracale, Camarines Norte.

Most of the deposits so far discovered, however, appear to be small or remain largely unquantified because of ore-dressing problems, the largest known deposits is that at Ayala, Zamboanga del Norte (6 million mt at 30% Zn, 2.5% Pb, and 0.3 Cu).

The potential for further discovery of these metals remains largely unknown.

Molybdenum

Molybdenum in the Philippines is associated with porphyry and contact-metasomatic deposits. Molybdenum-rich porphyries are found principally in southwestern Negros, molybdenum has constituted a by-product of copper mining.

Mercury

Mercury as cinnabar occurs in limited deposits in central Palawan, Albay (southern Luzon), Sibuyan Island, Romblon and Bataan (Central Luzon). Cinnabar occurs mainly as fissure veins, breccia fillings, cavity fillings and replenishments.

It was mines in Palawan from 1995 to 1975, with production peaking at 200 flasks (6.9 metric tons) in 1971.

Reserves are estimated at 16 metric tons at grades of 0.15 to 10.4 lb per metric ton.

Aluminum

Extensive deposits of bauxite occur in Bucas Grande Island, northeastern Mindanao and in Samar.

The Mindanao deposist are derived by weathering from ultramafic rocks and, as a consequence, are high in iron.

In Samar, bauxite is associated with lower Miocene karstic limestone, although it again may have been derived from ultramafic rocks, or from volcanic ash. Reserves here are calculated to be 116 million metric tons. Silica levels are high, often over 10%.