---
title: Lava rock in a terrarium | Glass Jar Garden
description: Lava rock (scoria): Light, porous red volcanic rock. Moss grips it well. In the jar it has holds water 17.5 % by volume, pore space 55 % by volume, weight...
url: https://glassjar.garden/guide/soils/lava-rock/
---

Soils and layers

# Lava rock (scoria)
Reusable

Light, porous red volcanic rock. Moss grips it well.

## What the simulation uses

- Holds water: 17.5 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 55 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 900 g/L (How heavy a litre is.)

- pH: 6.8 to 8 pH (How acid it keeps the soil.)

- Mould risk: none (How much fresh food it gives white mould; high-risk soils fuzz over in the first weeks.)

- Nutrients: low (Plant food it brings.)

- Presses down to: 97 % of its loose depth (How far pressing can pack it, keeping its weight.)

## Description
Bubbly volcanic rock, heavier than pumice, so most pieces sink. Chunks run from about one to three centimetres, good for drainage or small rockwork. It adds a few trace minerals and barely touches pH.

Also called red lava rock, black lava stone, volcanic rock.

Estimated, where sources were thin: bulk density, water holding and pH not measured on a cited page; basalt solid 2.4-3.1 g/cm3 (Engineering ToolBox) bounds it.

## Sources

- [en.wikipedia.org/wiki/Scoria](https://en.wikipedia.org/wiki/Scoria)
- [en.wikipedia.org/wiki/Lava_rock](https://en.wikipedia.org/wiki/Lava_rock)
- [greenaqua.hu/en/ada-kumu-st-09-black-lava-stone-150-g.html](https://greenaqua.hu/en/ada-kumu-st-09-black-lava-stone-150-g.html)

[Grow it in a jar](https://glassjar.garden/?guide=soils/lava-rock)

[Horticultural sand](https://glassjar.garden/guide/soils/horticultural-sand/) · [Leaf litter](https://glassjar.garden/guide/soils/leaf-litter/) · [All soils and layers](https://glassjar.garden/guide/soils/)