Malta Stone (Maltese Limestone / Globigerina Limestone)

Malta Stone, commonly referred to as Maltese Limestone or Globigerina Limestone, is a soft, fine-grained limestone primarily quarried in the Maltese Islands. It is a defining material in traditional Maltese architecture and is used widely across the Mediterranean. This stone derives its name from the abundance of Globigerina foraminifera (a type of microscopic marine plankton) embedded within its matrix.

Origin:

Geological Name: Globigerina Limestone

Type: Sedimentary rock – Biomicrite

Quarry Location: Malta and Gozo (central Mediterranean)

Formation Period: Oligocene to Miocene Epoch (23–34 million years ago)

Strata Layers in Malta: Lower, Middle (Softstone), and Upper Globigerina layers

Most used: Middle Globigerina (Softstone) layer – due to its workability

Color:

• Ranges from warm pale yellow, golden beige, to light honey
• Freshly quarried blocks appear golden, turning lighter/whiter with weathering and age
• Uniform tone, minimal visual variation

Texture & Pattern:

• Fine-grained and soft to the touch
• Homogeneous texture, with small fossil inclusions and shells (mostly Globigerina)
• Minimal veining or patterning
• Some rare occurrences of calcareous nodules or white streaks

Physical & Mechanical Properties:

• Density : 1.75 – 1.95 g/cm³
• Porosity : 20% – 30%
• Compressive Strength : 8 – 17 MPa (varies by quarry and depth)
• Flexural Strength : 1.5 – 3 MPa
• Water Absorption : 15% – 25% (by weight)
• Abrasion Resistance : Low (not suitable for heavy foot traffic)
• Mohs Hardness : 3 – 4 (soft)
• Slip Resistance : Low (unless textured or bush hammered)
• Thermal Conductivity : Low – good insulator

Chemical & Mineral Composition (% by weight):

• Calcium Carbonate (CaCO₃) : 90% – 96%
• Silica (SiO₂) : 1% – 4%
• Iron Oxides (Fe₂O₃) : 0.5% – 1.5%
• Clay Minerals : 1% – 2%
• Magnesium Carbonate (MgCO₃) : 0.2% – 1%
• Other Fossils/Organic Material : Minor traces

Cutting Sizes (in cm):

Standard quarry-cut blocks and sawn formats include:

• Blocks: ~100 x 60 x 40 cm or as extracted
• Cut-to-size tiles: 30 x 30 x 2/3/4 cm 40 x 20 x 2/3 cm 60 x 40 x 3/4 cm
• Custom sizes for architectural stonework

Surface Finish Options:

• Sawn (natural)
• Honed (matte/smooth)
• Bush-hammered (for anti-slip texture)
• Sandblasted
• Chiseled / Split-face (rustic use)
• Antiqued / Weathered finish (for restoration work)

Common Uses:

• Architectural cladding & facades
• Sculpture and carvings
• Restoration of historic buildings
• Interior & exterior wall facing
• Columns, balustrades, moldings
• Paving (low-traffic areas only)
• Garden walls, fountains, landscaping

Maintenance & Durability:

• Needs regular sealing if used in exterior or exposed applications
• Avoid acidic cleaners – high calcium carbonate content makes it sensitive to acids
• Periodic gentle cleaning recommended
• Weathering over time gives a characteristic aged appearance

Notable Properties:

Easy to carve and work – ideal for ornamental architecture

High porosity – allows for breathability in traditional structures

Aging beauty – color changes slowly with exposure

Cultural significance – declared a part of Malta’s architectural heritage