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Sandstone (Quartzarenite Rock)

Sandstone is a common rock used as vivarium rocks. They come in a range of different varieties depending on their origin. Figuring out which type is right for an aquarium can be difficult but hopefully, this guide will help understand a specific type that is great for your enclosure. The particular type this article will cover in-depth is called Quartz Arenite Sandstone.

Quick Stats:

Traditional Name: Quartzarenite

Common Names: Quartz Arenite, Arenite, Sandstone

Origin: Sedimentary Basins, Aeolian Environments

Habitat: Beaches, Upper Shoreline

Color: Red, Brown, Gray, Tan, Black, White, Yellow, Pink

Density (g/cm3): 2.00g – 2.60g

Hardness: 6 – 7

PH Impact: Neutral (No Effect)

Elemental Type: Sedimentary Rock (Quartz)

What Is Sandstone?

Sandstone is a clastic sedimentary rock composed of mostly sand-based minerals. This stone is the second most abundant sedimentary rock on the earth’s surface. It can be split into three specific categories depending on the grains that make up the majority of the stone: quartz, feldspar, or lithic. We will cover the quartz category more in detail today since they are stones very suitable for aquarium/terrarium use.

Quartz Arenite Rocks are a particular type of Sandstone that has a composition of quartz minerals greater than 90%. Like all Arenite Rocks, this stone contains less than 15% clay matrix cementing the siliceous grains together. This rock may also contain fragments of other rocks like chert.

Sandstone "Quartz Arenite Rock" Aquascape Tips

Quartz Arenite Rock Facts

Quartz Arenite is commonly referred to as Quartzarenite and consists of coarse-grained silica minerals visible to the human eye. This type of sedimentary stone is a very hard rock with a hardness scale of 6 to 7 making it very suitable for vivarium use. Due to the rapidly intense habitat Arenite forms in, it doesn’t weather easily and will last longer than most rocks in a number of biotypes. This is a very frequently used Sandstone for many beginner hobbyists to start out within aquariums/terrariums.

Description

Sandstones like Quartz Arenite have a very rough surface due to its mineral make up. It is a dense stone that lacks porosity by virtue of the clay matrix that fills the pores during formation. The average density of this stone is between 2.00 and 2.60 grams per centimeter making it a moderately heavy rock to work within large pieces.

A closer look at the mineral grains will reveal rounded sand-like fragments and small rocks cemented together. Quartzarenite rarely exhibits fossils or specs of fossil remains but it is possible to find some depending on the origin of the rock. Any Sandstone with a considerable amount of carbonated calcium (fossil) would be technically classified as a Limestone. These types of vivarium stones would be better suited for hardwater biotypes.

Quartzarenite is usually found in white, tan, or light grays attributed to the quartz mineral that makes up the rock. Furthermore, this type of Sandstone can also exhibit colors like red, brown, or pink when oxidized iron leeches on to the matrix during formation. A recurring pattern often found in Quartz Arenite Rocks are tan with waves of red or brown scattered across the surface. The darker waves of oxidized irons stained across the surface will often cause parts of the rock to become more tolerant of weathering… Creating a layered cleavage along the surface.

Habitat

Quartzarenite Rocks are typically found in high energy environments where a long-distance of mineral transportation accumulates. These areas can include both beach shores and aeolian environments. A mix of rounded coarse-grained Quartz and fine-grained clay eventually settle along the banks of marine environments and cement together forming this kind of Sandstone. Desert dunes can also attribute to the formation of Quartz Arenite Rocks. This is going to be a fast-flowing water type of environment for those looking for a suitable rock that won’t easily deteriorate under these conditions.

Environmental Influence

Due to the high energy environments that Sandstones from under, they are rather hardy rocks that won’t dissolve as fast as other sedimentary stones. This makes Quartz Arenite an inert rock suitable for many types of vivariums. On the hardness scale, this rock can range between 6 and 7. The strong composition of quartz is a long-lasting mineral that has no effect on buffering PH up or down in the water.

Be wary of darker colored Sandstones that carry relatively large amounts of stained oxidized irons in the clay matrix. Leeching of iron into an aquarium can be beneficial for plants but large amounts can be lethal for some inhabitants.

Vivarium Preference

Sandstone can be used in saltwater aquariums as well as freshwater. I’d recommend using this type of rock in tanks that consist of mostly softwater and have some type of plant. Some fish, like cichlids, for example, thrive in rocky enclosures stones like Quartzarenite would be ideal for. In terrariums that house reptiles, Sandstones like Quartz Arenite are a very natural way to provide a hardscape relative to a mimicked habitat.

Advantages

This kind of sedimentary rock can come in a wide variety of textures and colors. Sandstones like Quartzarenite are generally inert making them ideal for softwater enclosures. Inhabitants that require rocks in their tanks will find this stone very capable with no sharp edges due to its coarse-grained composition and fragment style breakage.

Disadvantages

Darker colors of Quartzarenite can leech small amounts of iron consistently. This can be lethal for fish and invertebrates that are sensitive to metals as well as harder water conditions. Regardless of the color, always keep a close eye on the vivarium when placing new rocks in it and clean all stones thoroughly before placing them in any type of tank.

Another concern is the weight of Quartz Arenite Rock. This amount of density per squared centimeter will make it potentially dangerous for the glass as well as the inhabitants if not secured correctly. Never place the rock on the bare bottom of the tank or up against the side glass. The concentrated levels of pressure focused on the edge of the rock could cause the glass to crack.

Buy Sandstone

This type of Sandstone can easily be acquired locally from nearby quarries. Though, finding a specific variation based on texture and color might be difficult depending on where you are in the world. For the sake of assuring the stones, you seek to purchase is safe for vivarium use, I’d highly recommend going with a source that is selling Quartz Arenite Rock specifically marketed for aquarium use. This will guarantee the product bought is authentic and 100% safe for tank mates. Click the image below to find out more about the current price and other relative info:

Sandstone Recommendations

Here are a few more useful tips when working with Quartzarenite for the first time. Inspect the rocks to verify the intended type of Sandstone has been acquired. Based on the color as well as the sturdiness of the stone, you should be able to identify the possible minerals compacted into the formation of this rock. Before placing Sandstone in an acidic vivarium, always do a quick vinegar test to assure there are no alkaline minerals contained within the rock. As usual, clean the rock to remove access dust or loose particles from the surface.

Cleaning Sandstone

In most cases, newly acquired Sandstone will need slight preparation before going into a vivarium. This will matter more for aquariums, ripariums, and paludariums since unclean stones can cause water to change color. Begin by placing stones in a bucket of cold water. Scrub and redip each stone thoroughly in the bucket of water. Rinse and repeat this process until you are able to place stones in a clean bucket of water and observe no noticeable change in color. Avoid using chemicals or strong water pressure on the sedimentary rocks so they aren’t worn down drastically and lose their aesthetics.

Breaking Sandstone

I always recommend breaking Sandstones with a simple chisel kit. Chiseling off parts of the rock along the fractures is a more controlled way to break Quartzarenite into desirable pieces. Carve out caves or holes and use the remaining fragments as additives to the substrate to create a more natural-looking environment. No matter which way the rock is broken up, make sure to wear safety goggles because parts of rock will go air born. Also, reclean rocks as needed once they are broken.

Rocks Similar To Sandstone

When designing a new enclosure for the first time… It would be best to stick with one type of stone to use as a hardscape. Furthermore, this type of rock can be hard to come by depending on where you are located in the world. If for any reason, you find Quartz Arenite difficult to acquire, or simply want to consider something different… There are a wide variety of stones to consider. Here are some other types of stones one might find are worth taking a look at in the place of this Sandstone:

Basalt "Lava Rock" Hardscape Guide
Pumice Rock "Floating Stone" Hardscape Guide
Dolomite "Elephant Skin Stone" Hardscape Guide

Conclusion

Quartz Arenite Rocks are great for both beginners and experienced hobbyist and work well in a number of different biotypes. The huge array of colors and textures give plenty of options to consider when used as a vivarium rock. Plan carefully and this rock will outlast the vivarium essentially becoming a reusable stone to have in a collection. If you’ve used Sandstones in the past, was it a Quartzarenite? If so, what colors did it exhibit and what type of vivarium was it used in?