Random Building Stone – Blue Sandstone

Searching for a true blue sandstone, we were delighted to source this beautiful random building stone from South Wales. Mostly blue grey with occasional bronze seams, we crop and dress this characteristically Welsh blue sandstone to give it a soft riven surface.


Quarried in South Wales and delivered to us as large blocks, the blue sandstone is then cropped to order by our skilled stone masons at our premises in Pontrilas. We split it along its natural beds to create random building stone of the high quality you expect from Black Mountain Quarries.

Suitable for random stone walling, risers and house building, our random cropped blue sandstone can also be provided in narrower widths for dry stone walling, with smaller pieces for cocks and hens.

One bulk bag of random building stone cropped to the standard 100mm – 150mm (4-6 inch) bed width will provide enough material for 3 to 3.5 square metres of facing stone. A wastage allowance of 10% should always be calculated into your figures when ordering.

We can also supply this building stone in our stone slips that are suitable for internal and external walls because of the thickness (20 -30mm) and the fact that it can be fixed directly it to wall like a heavy tile it hardly takes any space out of you room when used for interiors. When used for new builds it allows for a thinner wall therefore more space inside. With the use of our L shaped corners It is pretty much impossible to distinguish the stone slip and traditionally built stone work. Sold per the m2, L Shaped corners sold per the Linear metre.

What is random building stone?

Random building stone is cropped to a 100 – 150mm (4-6 inch) bed width as standard, providing at least one usable face per piece. (‘Bed width’ is the width of your footing). Heights and lengths are naturally random, hence its name – although you might also hear it called facing stone, random cropped building stone or random rubble in the trade.

One bulk bag of random building stone cropped to the standard 100mm-150mm (4-6 inch) bed width will provide enough material for 3 to 3.5 square metres of facing stone. A wastage allowance of 10% should always be calculated into your figures when ordering.

The natural variation in the shape and colour of real stone means that every piece of sandstone is unique. As such, working with random building stone requires the skills of a trained stone mason or appropriately experienced builder. It’s a technique that’s suitable for house construction and commercial / public buildings, restoration and renovation projects, boundary or retaining walls, dry stone walling, garden features and any kind of building project that involves the use of natural stone.

What if I need my stone cut differently?

If you need a non-standard bed width, our in-house stone cutting service can crop the stone accordingly. A custom bed width of 150mm – 225mm (6-9 inch), for instance, will provide you with a larger stone in all dimensions. Whatever bed width you specify, the heights and lengths of each piece will remain random.

We can also provide corner stones as required. These are made by cropping the random building stone as normal, then turning each piece of stone at right angles and cropping once more to make a right angled corner. They will have random heights and lengths and are ideal for chimneys, reveals, pillars etc.

If you need less than a tonne of random building stone, a different bed width or have a delivery address with tricky or limited access, please do give us a call – we’ll be happy to help.

Building and walling materials to match

For the building and walling stone that we lift from our own quarries (BMQ grey-green sandstone, Callow red sandstone, De Lank silver-grey granite) we offer matching ranges of flagstones, cobbles and paving, lintels and cills, steps and edging, wall coping and pier caps. All of these are available in standard sizes, or can be bespoke cut to your spec.

To offer the widest choice of colours, finishes and prices we also source stone from other UK quarries or from responsible suppliers around the world.

Many of these can be closely matched to other stone products, or can be successfully combined with complementary ranges – for example, using lighter coloured stone for cills and coping stones. If you would like advice, examples or ideas about combining stone ranges, do give us a call – or even better, pop in to our showroom.

For natural landscaping we provide boulders and rockery stones from all of our own UK quarries, with a choice of BMQ grey-green sandstone, Callow red sandstone, and Cornish silver-grey granite. These are available in various sizes from small rockery stones to 12 tonne boulders.

An important footnote about natural stone

Whilst we have done our utmost to ensure the stone and colours displayed on our website are accurate, they are to be used as a guide only. Because stone is a natural product, texture and colour will vary from piece to piece. As we work through the quarry, seams will yield slightly different coloured and shaped stones.

The building technique, quantity, colour and type of mortar used will all impact on the the look of the finished product. Please bear this in mind when ordering stone products. For larger projects or any projects where a specific look is required, we recommend that test panels are built.

We’ve provided a few tips on how to build a stone wall, and if you need any advice, give us a call.


Price per bulk bag
From £180.00 ex VAT
From £216.00 inc VAT


Random Tumbled Building Stone – Blue Sandstone

Price per bulk bag
£230.00 ex VAT
£276.00 inc VAT

Large Lintels

£150.00 ex VAT
£180.00 inc VAT

Flagstones – Black Tumbled Sandstone

Price per pack
From £440.00 ex VAT
From £528.00 inc VAT