The rocks of the Philippines can be mostly categorized as sedimentary rocks.
They’re often breakable rocks that have important uses in the economy based on a variety of accumulated research materials and data.
You’ll find igneous rocks, but if you’re a rock collector, you’ll mostly be captivated by how these rocks are used in society today.
Here are the most common rocks in the Philippines, and a guide to finding them whether you’re a casual collector or serious enthusiast.
Common Rocks Found In The Philippines (A Guide)
Coal is an organic sedimentary rock that forms when plant materials degrade in a swamp environment.
Vegetation deteriorates and falls into the oxygen-deficient water, leading to large amounts of peat production which later changes to coal.
Coal is one of the most important primary fossil fuels, occurring in stratified sedimentary deposits where plant debris often accumulates.
Collectible due to extraction methods, coal can be extracted from the earth and later used for electricity generation and cement production.
Coal can be dangerous to collect as the presence of nitrous oxide can cause respiratory diseases.
However, according to World-o-Meters, the Philippines produced roughly 13 million tons of coal in 2016, ranking the country 25th in the world in coal production.
Marble is often pink or white and has an unmistakable smooth texture. Its texture is one reason why there is a major industry for marble in the Philippines.
Marble is often crushed into powder form after being mined, and then later used to build foundations, railroad beds, and most noticeably, roads.
As a crystalline-looking rock, marble is composed of calcite and dolomite and requires a magnifying glass to see.
But marble only factors in at about 3-5 on the Mohs Hardness Scale.
Though it’s slightly tough, it’s easily scratchable, so much so that you’ll likely find scratches on its surface when you pick up the rock.
Marble is formed when limestone is subjected to heat and pressure that comes from the metamophorphism process.
Later, marble is mostly made into crushed or dimensional stone, but it’s easy to break, yet has a cool, sophisticated feel to it.
Most people can say they know when they’ve picked up a piece of marble.
The crystal-looking rock is often found in furniture and decorations, so the most avid rock collectors can look for it by having it installed in their home.
Shale is fine-grained sedimentary rock.
It’s located in the Bicol region but ultimately accounts for 70% of the Earth’s crust.
Easily splittable, shale is the most abundant sedimentary rock in the world.
You can find shale in the same place where you find sandstone or limestone, because those are the rocks commonly found among sedimentary deposits.
Shale is often used in the petroleum industry, as well as in the production of clay, which you’ll see turn up in some beautiful pieces of pottery.
Sandstone is a siliciclastic sedimentary rock composed mostly of silicate grains.
It’s often opaque, though it can be translucent, and can be found in the Mindoro Block, located on the East side of North Paloway Block, inside the Philippines Mobile Belt.
You might collect sandstone if you wander near a home construction project.
The grain will be 0.1 mm to 2.0 mm in size, and in terms of hardness, sandstone comes in at a 6 or 7 on the Mohs Scale.
Sandstone is among the most common sedimentary rocks, also accounting for about 10-20% percent of the Earth’s crust.
You can recognize sandstone if you can find some home construction or people building temples.
That’s because sandstone was once used to build basements and old-fashioned foundations, but calcite cemented sandstone, in particular, was subject to erosion due to acidic dissolution.
Conglomerate is a sedimentary rock typically composed of calcite or quartz.
The sedimentary rock has a smooth texture, can be found near beaches, and can be identified by its size, which is greater than 2 millimeters in diameter.
The longest conglomerate rock that can be found wouldn’t be longer than 10 millimeters across.
Conglomerate is formed when sediments of rounded casts at least 2 millimeters in diameter accumulate.
Conglomerate doesn’t have many commercial uses due to the ease in which the rock can disintegrate or break.
Still, conglomerate can be used as a substitute for other rocks and minerals when lower-quality materials are needed.
Found in many sedimentary environments, conglomerate can be used to fill materials for roads.
Andesite is an igneous rock.
As a volcanic rock, andesite is formed from lava that erupts from a volcano.
It has a light or dark gray color, sometimes brown, and is small enough that you need a magnifying glass to see.
Andesite is made up of dark and light minerals, and is an extrusive volcanic rock.
The product of extrusive magma andesite is also a rock that’s found on the surface of the earth around lava. You can expect a fine-grained texture.
Also, important fact: andesite is often found in a subduction zone environment.
Sometimes, andesite can also be found near eruptions around continental plate interiors.
Limestone is a soft, gray, white, yellow, or brown sedimentary rock composed mostly of calcium carbonate.
Limestone is formed when calcite and aragonite precipitate out of water consisting of dissolved calcium.
You can easily spot limestone when you see the gray, rectangular-like shape.
When you pick up limestone, you’ll notice its soft texture.
According to the Mohs Hardness Scale, which measures scratch-resistance, limestone is easily scratchable.
You can find limestone in Bohol Island, an oval-shaped island in the Philippines known as the “Last Ecological Frontier.
People flock to limestone around the area because the rock is known to have resilient qualities.
According to the Limestone Learning Center, limestone has historical significance.
The National Museum of Scotland states 5.5 million tons of limestone were used to build the Great Pyramid of Gaza.
Limestone was used then to show resilience.
These rocks are associated with the product of nature and man working to find benefit by using sedimentary rocks for various purposes.
Sandstone, coal, limestone, and conglomerate, as well as andesite, shale, and marble are some of the most common rocks you’ll find in the Philippines.