---
title: Black lava rock in a terrarium | Glass Jar Garden
description: Black lava rock: Very porous black volcanic rock that holds a little water in its pores and leaves pH neutral. In the jar it has holds water 15 % by volume,...
url: https://glassjar.garden/guide/hardscape/black-lava-rock/
---

Stones and wood

# Black lava rock

Very porous black volcanic rock that holds a little water in its pores and leaves pH neutral.

## What the simulation uses

- Holds water: 15 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 50 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 1000 g/L (How heavy a litre is.)

- pH: 6.8 to 7.2 pH (How acid it keeps the soil.)

## Description
Very porous black volcanic rock that holds a little water in its pores and leaves pH neutral. Moss takes to it readily, a quick way to get green on stone.

Also called black scoria.

Estimated, where sources were thin: look authored for the app; physical values estimated.

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

[Basalt](https://glassjar.garden/guide/hardscape/basalt/) · [Bogwood](https://glassjar.garden/guide/hardscape/bogwood/) · [All stones and wood](https://glassjar.garden/guide/hardscape/)