Brazilian Black Riven Slate Hearth Slab | 1200×900×20mm

Supplied by Bluesky Stone, based in Milton Keynes, specialising in Brazilian slate and limestone hearths available in standard stock sizes or custom-cut for trade and residential installations across England and Wales.

Looking for the ultimate log burner hearth or fireplace hearth stone? Engineered from direct-from-quarry Brazilian stone, this calibrated 20mm hearth slab combines rugged safety with contemporary style. Featuring a flat, subtle riven surface and clean 90° machine-sawn edges, it can be fully tailored to your exact dimensions through our custom-cut slate hearth fabrication service. Browse our full Natural Riven Slate Hearths range or our Slate Hearths range to compare sizes.

Highlights & Key Features

• Direct-from-Quarry Pricing: Brazilian slate sourced container-direct to avoid retail markups.
• Free Delivery on all full crate orders to England and Wales.
• 14-Day Crack Guarantee: If your slab cracks within 14 days of delivery (provided it is installed within that same 14-day window), we'll replace it completely free.
• Free Pre-Dispatch Photo Service: Every premium-grade order includes a free dispatch photo of your exact slab sent straight to you before delivery. Standard-grade slabs also include this service whenever a custom cutting or finishing service is added.
• Guaranteed Level Surface: A standard credit card slides smoothly across without catching on sharp ridges on the surface.
• Order a sample: Choose up to 2 free samples for a flat £5 delivery fee. See the texture and quality in person before committing to a full slab. Order your sample

Yes, this 20mm slate hearth is designed for heavy or wood-burning stoves and fireplaces.

• Heat Resistance: These calibrated slabs are engineered to withstand the weight and heat of a log burner. Not suitable for direct flame.
• Dimensions: 1200 x 900 x 20mm (+/- 1mm) with clean, 90° machine-sawn edges for a precise, contemporary fit.
• Weight: 61 kg per slab (2-person lift)
• Surface Finish: Subtle Natural Riven surface
• Edge Finish: Clean 90° machine-sawn
• Colour Profile: In its raw state, the stone features a Graphite Grey to Black profile with natural variation. Once sealed, the stone transforms to a much deeper, darker tone.
• Applications: Ideal for living rooms and dining rooms

This slate has been rigorously tested to ensure it meets the highest safety and durability standards:

• Slip Resistance: PTV 62 (Dry) / PTV 49 (Wet) – Rated as Low Slip Risk
• Flexural Strength: 19.6 MPa (48 Freeze-Thaw Cycles)
• Water Absorption: Less than 0.50% (High Frost Resistance)

We offer two distinct grades for this natural stone. Both share identical 20mm structural integrity and test results, but differ in visual selection.

• Standard Grade: Celebrates the raw character of natural stone with visible variations in texture, tone and pattern.
• Premium Grade: Hand-selected for aesthetic harmony; manually sorted to ensure a homogeneous appearance with a consistent colour tone across the surface.

See our guide to choosing between Standard and Premium slate grades, including our Credit Card Test for surface quality.

Guaranteed Level Surface — The Credit Card Test:
Regardless of grade, every slab must pass our internal surface tolerance test: a standard credit card must slide smoothly across the riven surface without catching or snagging on sharp ridges.

Tailored stone solutions for a perfect hearth installation

Our in-house fabrication team based in Milton Keynes provides professional tailoring for our entire range of Brazilian Slate and Limestone slabs. We offer three service tiers:

1. Professional Laser Guided Cutting

We provide precise laser-guided straight-line cutting to match your dimensions.

• Shapes: Squares, rectangles and pentagons
• T-Shape: We can supply 2pc T-Shape solutions - significantly easier to handle and reducing the risk of the stone cracking during transit and installation

2. Deep Clean & Seal Service

Bring out the true character and depth of your natural stone.

• Process: Each slab is deep-cleaned and washed to remove quarry dust and reveal its natural riven character.
• The Finish: We apply two coats of Stovax Dressing Oil. For Brazilian Slate, this transforms the raw graphite-grey profile into a deeper, darker, and more luxurious tone.

3. The "Signature Bundle" Package (Best Value)

Our most popular choice for a professional, "high-end" fireplace finish. This package includes everything in the cutting and sealing services, plus:

• Dressed Edges: We manually ease the edges and hone the sides of your stone (a process we call "dressing").
• The Look: This creates a smooth, chamfered edge that offers a truly wonderful, high-quality aesthetic for modern and traditional homes.
• Exceptional value - dressing the stone is included at no additional cost within this bundle, representing exceptional value.

See how our slate cutting, finishing, and sealing services work, from laser-guided cuts to the Signature Bundle finish.

Local to Milton Keynes?

• Free Click & Collect to waive delivery fees entirely.
• Trade-Ready service for local installers who require precision-cut material on short lead times. Contact our team for details.
• Free Samples - collect samples totally free from our warehouse to check colour and texture.

• Free Delivery: Applies to all full crates and covers all areas of England and Wales
• Single slab(s): If you're in England or Wales, your delivery cost shows automatically at checkout — no quote needed. Delivering to Scotland, Northern Ireland or the Islands? Delivery costs vary by location, so we provide a free personalised quote instead.
• Nationwide Logistics: Direct-to-site delivery via 3rd-party nationwide pallet delivery. Offloaded by pallet and delivered kerbside
• Customer quotes: Call 01908 46 46 56 or email drawings to sales@blueskystone.com.