Basalt vs Rhyolite: What Are They, And What's The Difference?

Basalt and rhyolite are two similar rocks that are often confused with one another. Due to their origins, they have some similarities in their appearance and location. However, upon taking a closer look, one will notice the primary difference in appearance is that basalt is closer to black in color while rhyolite is light grey.

Keep reading the article below to learn more about the origins, formation, location, and metaphysical or spiritual properties of each rock.

Basalt vs Rhyolite: Compared

What is Basalt?

Basalt is described as an extrusive igneous rock that is fine-grained and dark grey to black in color that weather to dark green or brown on the surface.

Basalt is mainly composed of olivine, pyroxene, and plagioclase with high contents of iron and magnesium.

Holes left by gas bubbles during formation generally leave the rock a coarse and porous texture.

Igneous rocks form when hot molten rock from beneath the earth, rises to the surface of the earth, cools, crystallizes, and solidifies.

Sometimes, they are also formed as they fill cracks or fissures of other rock beds, forming igneous dykes beneath the surface.

Basalt is one of Earth’s most abundant bedrocks, covering more of the Earth’s subsurface than any other type of rock.

Although you will find it on the continents it is particularly more common in ocean basins at divergent oceanic boundaries.

This is because convection currents draw up the hot rock from deep within the Earth’s mantle and deposit it on the ocean floor.

Interestingly, basalt is also an abundant rock type on the Moon and Mars as well.

Basaltic lava flows underlie much of the moon’s surface in areas known as “lunar maria” and extensive eruptions have resurfaced vast areas of the Moons surface.

The Olympus Mons, the largest volcano in our solar system, is a shield volcano formed from basaltic lava flows.

Basalt is commonly used as aggregate for construction materials such as concrete, pavement, and asphalt.

It can also be cut into dimensional stones that can be used for floor tiles, statues, or other structures.

For those interested in the metaphysical and spiritual properties of basalt, some people believe that basalt symbolizes strength and courage and is helpful by creating stability during change or turbulent times.

What is Rhyolite?

Rhyolite is another extrusive igneous rock that is primarily pink or grey in color.

The grains in this rock are apparently so small that they can be difficult to see with the naked eye.

Rhyolite is primarily composed of quartz, plagioclase, and sanidine, with small amounts of hornblende and biotite.

Oftentimes, they contain crystals, opals, or other glassy materials.

Small holes or “vugs” are also found on the surface due to trapped gasses during their formation.

Most rhyolites are formed when granitic (rock made from granite) magma erupts from the Earth’s surface.

Any rhyolite that forms on the surface are called phenocrysts and have large crystals while rhyolite formed beneath the surface is called groundmass and will have smaller crystals.

Interestingly, fire opal can sometimes be found filling the holes and cavities of rhyolites.

They tend to be bright orange-red in color and are glassy and transparent.

Famous deposits can be found in Mexico.

This rock is primarily found near sites of volcanic eruptions at continental divides but is rarely produced in oceanic eruptions.

Volcanic eruptions of granitic lava are extremely rare, with only 3 known eruptions since 1900.

However, they also tend to produce some of the most explosive eruption events in Earth’s history.

Historically, rhyolite was commonly used out of necessity to create stone tools and weapons such as arrowheads, axes, and scrapers.

Today, rhyolite is rarely used because it is so easily fractured.

Some people also believe that rhyolite also facilitates change and progress by increasing one’s vitality and strength.

How are Basalt and Rhyolite similar?

Basalt and rhyolite are both extrusive igneous rocks that are formed when molten rock comes near or explodes out of the earths surface.

They are each fine-grained and often have holes caused by trapped gases.

Both rocks are thought to have beneficial metaphysical and spiritual properties that allow one to cope more easily with challenges or change.

How are Basalt and Rhyolite different?

Basalt tends to be dark grey or black whereas rhyolite is a lighter grey or pink color.

Though both fine-grained, rhyolite has finer grains that are more difficult to see.

Although both basalt and rhyolite form near continental divides, basalt is more commonly found in oceanic basins whereas rhyolite is rarely found there.

Basalt is extremely common on the Earth’s subsurface whereas rhyolite forming granitic eruptions rarely occur leading to less formation of the rock.

Crystals, opals, and other glassy rocks are often found within rhyolite and not in basalt.

Basalt is mainly composed of olivine, pyroxene, and plagioclase with high contents of iron and magnesium whereas rhyolite is primarily composed of quartz, plagioclase, and sanidine, with small amounts of hornblende and biotite.

Why do people confuse Basalt and Rhyolite?

People may confuse these two rocks because both basalt and rhyolite are extrusive igneous type rocks that are found near sites of volcanic eruptions or flooding.

They both have fine-grained and porous textures due to present gases during their formation.

The easiest way to differentiate the two rocks is by their color with basalt being dark grey to black and rhyolite being a light pinkish grey.