There is a big chance many of us have only heard about dolomite recently, when the mineral made it to the headlines because of the Department of Environment and Natural Resources’ (DENR) Manila Bay “beach nourishment” project.
Crushed dolomite boulders exported from Alcoy, Cebu had been spread along the shoreline of Manila Bay to enhance the aesthetic beauty of the bayfront. Undersecretary Benny Antiporda told ANCX last week that putting “white sand” on Manila Bay is the department’s way of giving a spark of hope in this time of pandemic—and to also promote cleanliness and environmental awareness.
But what is dolomite, really? What is it made of and what are its main uses—apart from, well, “beach nourishment”?
Bountiful in Visayas
According to a geologist ANCX spoke to, dolomite is a naturally occurring mineral just like limestone. They belong to the same calcium carbonate mineral family, which are basically formed under marine conditions. This is the reason why dolomite is more abundant in the Visayas region—around Cebu, Bohol, and some parts of Western Leyte—which are considered marine sedimentary basins.
Kevin Garas, a senior geologist at the Mines and Geosciences Bureau (MGB) explains that dolomite is formed due to different geological events that occur over millions of years, as well as the introduction of magnesium.
“Kaya dito sa Pilipinas, kapag sinabing ang bato ay dolomite, hindi ibig sabihin na 100% dolomite mineral lang ang laman. Pwede syang magkaroon ng calcite, dolomite, or other carbonate minerals,” he tells ANCX in a phone interview.
Garas says older rocks have the tendency to contain more dolomites. “Ang earth is 4.6 billion years. Sa ibang bansa, dahil iba ang kanilang geologic setting, mas matanda ang mga formation ng mga bato nila—mga 200 million years. Meron pa silang umaabot ng 500 million years. Sa Pilipinas, bata kasi tayo in terms of geology, so this could be the reason why dolomites are not as abundant here,” he explains.
A dolomite industry?
Based on a 2018 MGB report, there is only one dolomite quarry in the Philippines. Compared to businesses that deal with metallic or non-metallic mines, the dolomite industry is not very popular in the country, notes Garas. “Dalawang possibilities yan—either kaunti lang talaga ang dolomite sa Pilipinas o pwedeng hindi pa naaaral o nadi-discover ang mga dolomite deposits natin. Wala pang ganoong karaming data,” he says.
According to a news release published by MGB Region 7, Cebu is among the few provinces in the country where economically mineable deposits of dolomite can be found. Dolomite occurs in several of the city’s municipalities but the main deposit is found in the Alcoy and Dalaguete areas.
Currently, Dolomite Mining Corporation (DMC) is mining/quarrying the dolomite found in the town of Alcoy, particularly in Barangay Pugalo, the news release also mentioned.
Garas says dolomite is more commonly used in the Philippines as a raw material for steel production, glassmaking, and soil conditioning.
“The main ingredient for glassmaking is silica (silicon and oxygen). Other minerals are added to increase the quality of the glass. One of the materials that can be used is dolomite,” he says.
Dolomite is also utilized for soil conditioning—to adjust the acidity or alkalinity of the soil. “Halimbawa, kung acidic ang lupa, hindi sya magandang taniman, itinataas ng dolomite ang alkalinity nito,” he adds.
A 1995 study published on the Journal of Animal and Feed Sciences, which Garas led us to, reveals that adding dolomites, among other minerals, to the feeds of young cattle, tend to increase the animals’ absorption of calcium, magnesium, and potassium, resulting in their significant weight gain.
Its more popular use, as we had discovered recently, is as substitute for white sand in a beach nourishment project.
Used in Cebu resorts
Speaking during the House deliberations on the DENR budget last week, Secretary Roy Cimatu, also responded to inquiries on the now controversial mineral. He said “dolomite will clean the water from acidic to alkaline” referring to Manila Bay’s waters. He also noted that dolomite is already being used in several resorts in Cebu as well as in aquariums.
In the same Rappler story, Environment Undersecretary Jonas Leones also defended the Manila Bay project saying that the use of artificial sediment and "beach nourishment" have been done in other countries.
The previously mentioned MGB news release notes that on August 26, MGB-7 Regional Office issued an Ore Transport Permit (OTP) to PMSC to transport 3,500 WMT (wet metric tons) of processed dolomite (size -5mm) with cargo destination at Manila Integrated Cargo Terminal, Manila City. This shipment is the reported ‘white sand’ that was dumped along the Manila Bay shoreline.
According to the MGB Region 7 news release, PMSC-Alcoy Plant has been issued a Mineral Processing Permit (MPP) by the MGB and is on its second five-year term, which will expire in 2023. The MPP has a maximum term of 25 years.
In the Philippines, the dolomites of PMSC-Alcoy Plant are shipped to various buyers/end-users in Misamiz Oriental, Pasig City, Davao City, Manila, as well as in the cities of Mandaue and Lapu-Lapu in the Province of Cebu. The company also has markets in Taiwan and Japan. The news release did not specify for which purposes or industries the dolomites are used.