Pavestone Red Lava Rock 0.5 Cu Ft Bag, Lightweight Volcanic Stone

Why It Is So Light

The lightness is not the mineral, it is the voids. Scoria forms when dissolved gas comes out of molten rock as it erupts, and the rock solidifies before the bubbles escape. What you are carrying is basalt with a large fraction of the bag volume being trapped air. That is why a bag covers the same ground as gravel for a fraction of the lifting, and why it is the sensible pick for roof decks, planters and anywhere weight on a structure matters.

The Red Is Natural, and That Matters

The color comes from iron in the rock oxidising at eruption temperature, the same chemistry that reddens rock generally. Red and black lava rock are typically the same stone, differing in how much they oxidised. Because it is mineral rather than a coating, there is no pigment to leach into soil or bleach out the way dyed wood mulch does. Retailers sometimes claim it will not fade. Pavestone makes no such claim and neither will we. What does happen over years is that dust, mineral deposits and algae dull the surface, and a rinse usually brings much of the color back.

Drains Freely and Holds Moisture at the Same Time

This sounds contradictory and is not. Water passes quickly through the gaps between the stones, while the vesicles inside each stone hold moisture. That combination is why crushed scoria is used as a hydroponic substrate and as drainage stone, and it is behind Pavestone’s claim that the product retains moisture. It is also near neutral in pH, unlike marble or limestone chips, which push soil alkaline over years.

Specifications

Fire Pit Use, and the Warning That Goes With It

Pavestone specifically endorses filling the cavity of a fire pit with this rock for heat dispersion, and lava rock was the standard gas grill medium for decades because its open vesicles let steam escape rather than building pressure. That said, industry guidance distinguishes fire rated lava rock from decorative landscape rock, and porous stone that has soaked up rainwater can crack or pop when heated as trapped water flashes to steam.

• Let it dry completely before lighting a fire pit or grill after rain.
• Make sure the pit drains. Never light one with standing water in the burner pan.
• Replace it every few seasons. It degrades and collects grease and soot.
• If in doubt, buy a fire rated product. Call us and we will be straight with you about the difference.

Honest Drawbacks

• It is sharp. Scoria fractures with abrasive edges. It is unpleasant barefoot and hard on the knees when weeding, so it is the wrong choice for play areas and dog runs. Pea Pebbles is the product for those.
• It absorbs heat. Dark stone raises soil and air temperature more than pale stone. Good for xeric planting, punishing for shallow rooted moisture lovers in full sun.
• It adds nothing to the soil. Inorganic mulch does not decompose or feed soil life the way bark does.
• It crushes under traffic into a red grit that stains concrete, so keep it out of drive lanes.
• It is very hard to remove. Light angular fragments migrate into soil and under fabric. Treat it as a semi permanent decision.

The manufacturer's technical data sheet (coverage, joint width, cure and rain-safe times) and safety data sheet are collected in the TDS and SDS library. Every figure on this page comes from those sheets.