There are several different uses for lava rock. Lava rock, also known as volcanic rock, is quite versatile. It is the product of volcanoes and filled with air bubbles which makes it very light.
Lave rock is used in gas barbecues. The flames heat the lava rock which then act like charcoal in a regular grill to cook the food very effectively and cleanly. You do need to keep the rocks clean between uses or you can simply replace them.
Lava rock can make effective landscaping in a flower bed or border. It’s not so effective as a pathway due to the irregular shape. Lava rock can be colored to give it a very startling effect in the garden.
Lave rock is often used in aquariums and terrariums. It looks good and provides texture to the area but has the advantage of being much lighter than normal rocks so it won’t put stress on the glass.
Some lava rock is solid obsidian and can be used in surgical tools as it’s even sharper than steel and gives a much cleaner cut. Historically, this type of lava rock, which has no air bubbles, was used by Native Americans to make arrowheads.