01 / Geological family
Origin and composition
- Geological family
- Igneous
- Origin and composition
- two-mica granite
- Origin
- Porto and its surroundings, Portugal
- Appearance and identification
- pale grey and white colours with yellowish weathered varieties
Igneous rocks form when molten material solidifies. Cooling underground can produce visible crystals, as in granite; cooling at the surface can produce fine grains, cavities or porphyritic textures. Basalt, granite and many porphyries illustrate different compositions and structures. The commercial term granite can also include other geological rock types: a specification benefits from both the trade name and petrographic description.
02 / History and curiosities
History and curiosities
The Torre dos Clérigos and many city buildings show its use.
03 / Applications and design
Applications and design
Masonry, façades, stairs, paving and street furniture.
Finishes and processes ↗04 / Technical interpretation
What to ask your supplier
Yellow tones can reflect alteration; describe material condition as well as colour.
05 / Care and maintenance
Care and maintenance
Remove dust and grit with soft tools, wash with a compatible neutral cleaner, then rinse and dry. Identify composition before using stain or scale removers: carbonate stones are acid-sensitive. Test every treatment in an inconspicuous area. An impregnator can reduce absorption but does not make a material waterproof or stain-proof.
Thoughtful cleaning, protection and maintenance ↗06 / Photograph
Photo gallery
Photographic example: appearance and colour vary with quarry, batch, light and finish.
07 / Sources and further reading
