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Tumbled basalt stones, 20mm rocks from Rock n Soil, showcasing smooth, dark volcanic stones suitable for landscaping or decorative use.
Close-up of tumbled basalt stones, 20mm rocks from Rock n Soil, showcasing smooth, dark volcanic stone surfaces.
Tumbled basalt stones, 20mm rocks from Rock n Soil, showcasing smooth, dark volcanic stones suitable for landscaping or decorative use.
Close-up of tumbled basalt stones, 20mm rocks from Rock n Soil, showcasing smooth, dark volcanic stone surfaces.

Tumbled Basalt Stones (20mm)

Only 2 left
SKU: RTB20
$740.00 inc. GST

Cubic Metre Calculator

Need to calculate how much you’ll need? Use our cubic metre calculator below.

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Size
For ordering ¼㎥, ⅓㎥ and ½㎥ quantities please call the office on (07) 3245 5677
Please note that deliveries to postcode 4178 (Fishermans Island) may incur additional toll fees.
Bulk Order Delivery: Large quantities or multiple bulk products may incur additional delivery charges. We'll contact you before applying any extra charges.
Frequently Asked Questions

Our Tumbled Basalt Stones (20mm) are smooth, charcoal-coloured stones that are a great choice for modern landscape designs. Because they have been tumbled, they are smoother underfoot than many other bulk stone options, making them an excellent choice if you're looking for a stone that is comfortable to walk on.

These stones are commonly used for:

  • Garden beds
  • Decorative ground cover
  • Pathways and around stepping stones
  • Pot and planter toppings
  • Water features
  • Around feature trees and shrubs

To calculate how much Tumbled Basalt Stones (20mm) you need for your project, measure the length and width of the area where the stones will be placed.

Next, determine the desired depth of the stones. The required depth will vary depending on your project and the area you need to cover.

Once you have your length, width, and depth measurements, you can use our cubic metre calculator above or calculate the volume manually using the following formula:
Volume = Length × Width × Depth

Recommended Depth: As a general guide, we recommend laying decorative stones at a depth of 40–50mm. However, the ideal depth will depend on your project and the size of the stones. Larger stones may require a deeper layer for even coverage, while smaller stones can often be laid slightly thinner.

Yes. Tumbled Basalt Stones (20mm) are an excellent choice for pool surrounds, ponds, fountains, and water features. Their smooth, rounded finish and natural dark colouring create an elegant look that complements water features and contemporary landscape designs.

Tumbled Basalt Stones (20mm) do not require sealing. However, applying a suitable natural stone sealer can provide additional benefits, including protection against staining, enhanced colour, and easier ongoing cleaning and maintenance.

Note: If you decide to seal your stones, the colour may deepen and become darker. Whether you choose to seal them will depend on the appearance you want to achieve and the environment in which they are installed.

Bring a sophisticated, natural look to your garden with our Tumbled Basalt 20mm pebbles. These semi-rounded stones have a deep charcoal-grey hue that works perfectly around pavers, garden beds, pathways, and feature landscaping areas. Locally sourced and tumbled for a smooth finish, they’re comfortable underfoot and add a striking contrast to lighter garden elements.

Tumbled Basalt Benefits:

  • Ideal for pathways, garden beds, and decorative features

  • Smooth, tumbled finish for a premium feel

  • Locally sourced, high-quality basalt

  • Complements other landscaping elements and lighter coloured rocks

Specifications:

  • Size: 20mm

  • Sold in increments of 1/4m³, 1/3m³, 1/2m³, and 1m³

  • Delivered

Note: There is colour variation in the stock of this product. We recommend viewing the colour in our yard before purchase. Imagery may appear darker than stock in the yard.

Looking for a true black finish?
Natural stone quarried from the earth cannot achieve a perfect jet-black colour and will always present as dark grey or charcoal. If your project vision requires a deeper black appearance, our Kashmiri Black polished pebble range—which is cut and polished rather than naturally tumbled—may be a better fit. These are available in small bags and offer a richer, darker tone suited to feature areas.

Note: Rock colours appear darker when wet. For an accurate shade, view them dry or ask our staff for dry samples or photos of the product when dry. If you receive a delivery when it is/or has been raining, wait for at least 24 hours of dry weather to view the true shade of your stones.

 

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