How much stone do I need for the ground?
For pebbles and gravel:
• ±80 kg per m², based on a 5 cm layer.*For grain sizes >32 mm a thicker layer is required.• Consumption per big bag: 1000 kg = 0.625 m³.
• Coverage: ±12.5 m² with a 5 cm layer.
For pine bark:
• ±70 L per m², based on a 5 cm layer.
• Consumption per big bag: 1000 L = ±1 m³ = ±600 kg
• Coverage: ±14 m² with a 5 cm layer.
For volcanic rock, slate and chamotte:
• ±50 kg per m², based on a 5 cm layer.
• Consumption per big bag: 1000 kg = ±1 m³
• Coverage: ±20 m² with a 5 cm layer
How much stone do I need to fill a gabion?
Density of ±1,650 kg per m³.
The calculation is easy to understand with an example: for a gabion measuring 100x50x30 cm, do the following:
1x0.5x0.3 = 0.15 m³
0.15x1,650 = 247.50 kg of stone.
*It is always a good idea to allow 5% extra, as gabions widen slightly when filled and always take a little more stone than the theoretical calculation.
PLEASE NOTE! Before buying, read this information about gravel and pebbles
Grain sizes are sieve sizes, not exact measurements
When we talk about stone of, for example, 60-80 mm, we mean that the stones pass through an 80x80 mm square mesh and do not pass through a 60x60 mm one. A stone 100 mm long and 65 mm wide can easily pass through that 80x80 mesh, because the mesh sorts by the width of the stone as it passes through, not by its total length. That is why it is normal for a percentage of stones to have some dimension above 80 mm or below 60 mm.
Machines do not sort 100% accurately
In addition, no industrial sorting process is perfect: there is always a small percentage of stone which, due to speed, irregular shape or pieces overlapping on the belt, does not pass correctly through the corresponding mesh and slips into the grade, so stones larger than stated may occasionally appear. This is normal for this type of product and is not considered a defect.
Breakage of pebbles
In pebbles over 60 mm, up to 10% of the stones may break during sorting, washing, loading and unloading. We currently have no machinery that completely prevents this breakage. The product photos show only real pieces: broken pieces have not been removed.
Dust and sand in the product
This product is not washed, so it contains dust, sand and even traces of other materials from processing and transport. This is no problem for its use: the stone washes itself over time, or you can rinse it with water before use if you prefer.
Colour can vary considerably between batches
This is natural stone, and the colour changes from one batch to another, sometimes noticeably. This is especially important for multi-toned stones such as Blanco Rosa: some batches come out very white and others very pink, within the same product. If the exact shade is very important for your project, we recommend not buying this type of product online, as we cannot guarantee that the batch you receive will match the photo or a previous purchase.
Returns
Please bear in mind that returns, especially of 1,000 kg big bags, are usually complicated and expensive because of the weight and volume of the material. If the return is not due to an error on our part, the costs and arrangement of the return transport are borne by the customer.
The Black Granite Boulder is one of the most striking and robust pieces in our collection. Thanks to its size and texture, it is the material of choice for landscaping projects seeking a solid, natural look with strong visual impact.
Important note about colour and material
It is essential to clarify that "Black" is the commercial name of the raw material (the type of granite rock it comes from). As can be seen in the detailed product photographs, the stone is not solid or jet black. It shows an elegant range of dark greys, anthracites, and mineral veining typical of authentic granite. This tonal variation is precisely what gives it its natural beauty and keeps the garden from looking artificial.
Large Format (100-200 mm): A bold size, ideal for viewing from a distance and for filling large spaces with fewer pieces.
Granite Hardness: Unlike other limestone boulders that can crumble, this granite is virtually indestructible. It withstands frost, intense sun, and decades of wear without flinching.
Effect with Water: When installed in rainy areas or near fountains, the colour deepens, revealing rich nuances that enhance any outdoor design.
Gabion Filling: It is the perfect size for gabions. Its structural robustness and grading ensure the cages are packed solidly, creating decorative or retaining walls with a professional, modern finish.
Focal Points in the Garden: Thanks to its scale, it works wonderfully for creating groups of decorative stones, surrounding century-old trees, or naturally marking out areas.
Modern Landscaping Projects: Pairs perfectly with white gravels or composite decking, adding a sober, elegant contrast.
Material: High-density natural granite.
Colour: Anthracite grey / dark (commercial name: Black Granite).
Grading: 100-200 mm (large size).
Maintenance: None. Being a low-porosity stone, dirt does not adhere easily and washes off with rain.
If you want the strength of granite in a generous size and a sober tone, the "Black" Boulder is the toughest, most honest choice for your project.
For gravel and pebbles you need approximately 80 kg per m² with a 5 cm thick layer. A 1,000 kg big bag (0.625 m³) covers about 12.5 m² at that thickness. For slate, volcanic rock or chamotte the amount is lower, around 50 kg per m² (20 m² per 1,000 kg big bag).
For decorative use a layer of about 5 cm is recommended. With grain sizes above 32 mm it is advisable to increase the thickness slightly so that the stone covers the surface well.
Yes, it is recommended to lay a geotextile (weed control) membrane before spreading gravel or pebbles. It prevents the stone from mixing with the soil and reduces weed growth.
The grain size (e.g. 60-80 mm) indicates the sieve size the stone passes through, not an exact measurement. A stone 100 mm long can still pass through an 80 mm mesh if its width allows, and no sorting process is 100% perfect, so it is normal to find some percentage of stone outside the stated range.
Yes. In pebbles over 60 mm, up to 10% of the stones may break during sorting, washing, loading or transport. It is not a defect: the photos show real pieces, with broken ones not removed.
No, the product may contain dust, sand or residues from the extraction and transport process. It does not affect its use: over time (rain, watering) it cleans itself, or you can wash it yourself before laying it.
No. As it is natural stone, the colour can vary from one batch to another, especially in mixed-tone stones. If the exact shade is important for your project, we do not recommend buying without seeing it first, as we cannot guarantee it will match the photo.
The average density is about 1,650 kg per m³. For example, for a 100x50x30 cm gabion (0.15 m³) you will need approximately 247 kg of stone. It is advisable to allow 5% extra, as a little more stone than calculated usually fits when filling.
