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Granite is a coarse-grained durable rock with a crystalline structure. Rounded by physical weathering processes. It has many aesthetic and practical uses, e.g. for monuments, gravestones and kitchen bench tops.
The smooth surfaces make rounded rocks especially suitable for scratch tests to determine hardness.
Igneous: Formed from molten magma cooling and solidifying while deep underground (therefore a 'plutonic igneous' rock).
Source location: Westland.
Sizes: Choose from dropdown menu either Shelf specimen (300–800g), or Hand specimen (less than 300g)
Note: Images are examples of specimens only. Sizes and shapes will vary.
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Structure
Granite is a coarse-grained plutonic igneous rock with a crystalline structure. It is composed mainly of quartz, feldspar, and mica minerals.
Type
Plutonic igneous.
Physical properties of granite
- Colour: Can have a wide range of colours, including white, grey, pink, red, or black. It often exhibits a speckled or mottled appearance.
- Lustre: Has a crystalline lustre, which can vary from shiny to slightly dull, depending on the mineral composition.
- Hardness: A hard rock, ranking around 6 to 7 on the Mohs scale of mineral hardness.
- Density: Ranges from 2.6 to 2.7 grams per cubic centimetre.
- Fracture: Exhibits a granular fracture, breaking along interlocking mineral grains.
General properties of granite
- Composition: Consists mainly of quartz, feldspar, and mica minerals. The proportions of these minerals can vary, resulting in different types of granite.
- Coarse-Grained Texture: Has a coarse-grained texture due to its slow cooling and crystallisation deep within the Earth's crust.
- Durability: Highly durable and resistant to weathering, making it suitable for long-lasting applications.
- Heat Resistance: Exhibits excellent heat resistance and can withstand high temperatures without significant deformation or damage.
- Low Porosity: Has relatively low porosity, making it less susceptible to water absorption and freeze-thaw damage.
Uses of granite in New Zealand and worldwide
- Construction: Widely used as a construction material for building facades, walls, flooring, countertops, and monuments due to its durability and aesthetic appeal.
- Dimension Stone: Is cut and polished into slabs or blocks for architectural purposes, including countertops, tiles, and decorative elements.
- Landscaping: Used in landscaping projects for pathways, steps, retaining walls, and decorative features, adding natural beauty and durability to outdoor spaces.
- Monuments and Memorials: Granite's durability, variety of colours, and ability to retain inscriptions make it a popular choice for monuments, gravestones, and memorials.
- Sculpture: Used by artists and sculptors to create sculptures and artistic installations due to its hardness and ability to hold intricate details.
- Industrial Applications: Used as an aggregate in concrete, for road construction, and as a raw material for manufacturing.
- Geological Studies: Studied by geologists to understand igneous processes, the formation of plutons, and the history of Earth's crust.