What Is the Purpose of Lava Rocks?

Lava rocks form when molten rocks from erupting volcanoes fly through the air and land on the ground. They are then collected and used for a variety of home and garden purposes. Factors such as consistency and size determine the price of the rock and what it will be used for. Lava rock is most commonly used in landscaping but is also used in aquariums, barbecue grills, jewelry and more.


Lava rock has many uses.
From the volcano to your backyard.

Lava rock works very well in landscaping as it does not fade, controls weeds, retains moisture and protects plant roots.  Should you decide to use lava rocks in your flower bed, first rake all leaves and plant debris away from all plants.

Edging is a good idea when using lava rocks since it helps keep the rocks in the flower bed and away from the lawnmower.  Lining flower beds with lava rocks is an excellent way to keep weeds out.

Do not let the lava rocks rub against the plants, as they can cut them.  Also, try using lava rocks around backyard ponds to hide water pumps and hoses.


Lava rock is often used as aquarium beds

Crushed red or gray lava rock is often used for lining the bottoms of fish aquariums.  It protects underwater plants and the young fry, which are often found underneath the rocks if rocks are removed from the aquarium.

Crushed lava rock is also useful as a filter medium in aquariums.  For such use, crushed lava rock comes in 50-pound bags; find such bags at stores like Kmart or Target and at garden supply stores.

One 50-pound bag for aquarium use is said to last a very long time.  Prep the rock for use in your aquarium by running water over the rock until the water runs clear.

Be aware of sharp edges. 


Use lava rock for grilling.

Barbecue grills often come equipped with lava rocks.  Lava rocks are excellent to use when barbecuing, as they reflect and retain heat when grilling.

Do not use them to replace fuel or charcoal; rather, use them to evenly distribute heat.  They also prevent flareups and help with vapor drippings.

Precaution is needed when grilling with lava rocks as food cooked at high heat can permeate the rocks.  This can cause excessive smoking when the food burns off.

Lava rocks can also become saturated with grease, which can cause flareups.  Over time the rocks will crumble and should be replaced every season or two.

Roadway and Footpath Traction

Lava rock makes excellent traction on slippery highways.

Some types of lava rock are very abrasive and sharp and are used as roadway traction.  They are particularly helpful in icy conditions; you might consider keeping a small bag of lava rock in your car or truck during the winter for this reason.

Just be sure the bag is not so heavy that it weighs your vehicle down.  Lava rock can also be used as traction on slippery walkways during winter months and in making areas for parking cars.

Jewelry and Other Uses

A certain type of lava rock called obsidian was using to make arrowheads by American Indians.  Today it is used for making jewelry and surgical instruments.

Obsidian does not have as many air bubbles in it as other forms of lava rock.  Obsidian is used in combination with sterling silver and leather in earrings, necklaces, bracelets and more.

It can be purchased in beaded form for making your own jewelry.  Cube, round, oval, coin, flat and free form are just some of the bead types lava rock can be purchased in.

About the Author

Kent Page McGroarty has worked as a writer since 2006, contributing numerous articles to various websites. She is a frequent contributor to the health and fitness sections of the online magazine EDGE Publications and holds a Bachelor of Arts in English from Saint Joseph's University.

Photo Credits

  • lava rock image by Alison Bowden from Fotolia.com
  • Mount Teide image by Dawn from Fotolia.com
  • aquarium fish 4 image by cherie from Fotolia.com
  • steaks on barbecue grill image by FrankU from Fotolia.com
  • Winter roads image by Dumitrescu Ciprian from Fotolia.com