---
title: Round boulder in a terrarium | Glass Jar Garden
description: Round boulder: One rounded grey stone is all some layouts need as a centrepiece. In the jar it has holds water 1 % by volume, pore space 3 % by volume,...
url: https://glassjar.garden/guide/hardscape/mini-boulder/
---

Stones and wood

# Round boulder

One rounded grey stone is all some layouts need as a centrepiece.

## What the simulation uses

- Holds water: 1 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 3 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 2550 g/L (How heavy a litre is.)

- pH: 7 to 7.5 pH (How acid it keeps the soil.)

## Description
One rounded grey stone is all some layouts need as a centrepiece. It is dense, holds no water and does nothing to pH.

Also called cobble.

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

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

[Rose quartz](https://glassjar.garden/guide/hardscape/quartz-rock/) · [Ryuoh stone](https://glassjar.garden/guide/hardscape/ryuoh-stone/) · [All stones and wood](https://glassjar.garden/guide/hardscape/)