Facts about Granite
- 09
Radioactive decay of uranium, thorium, and potassium within granite contributes measurably to Earth's background radiation, making granite slightly more radioactive than most other common rocks.
- 08
Yosemite National Park's Half Dome granite formation, rising 5,000 feet from valley floor to summit, formed approximately 100 million years ago and represents one of Earth's largest exposed granite batholiths.
- 07
Granite bedrock underlying Scandinavia was scraped down by glaciers during the last ice age, lowering some peaks by as much as 3,000 feet and creating the region's characteristic U-shaped valleys.
- 06
Countertops made from granite require sealing every one to three years because the stone's porosity allows liquids to penetrate and cause staining without protective coating.
- 05
Granite's extreme hardness, rated 6 to 7 on the Mohs scale, makes it resistant to weathering and explains why granite formations often remain visible for over 300 million years.
- 04
Ancient Egyptian obelisks, including the 240-ton needle of Cleopatra's Needle, were carved from single granite blocks quarried in Aswan around 1500 BCE using copper tools and wooden wedges.
- 03
Cooling granite takes approximately one million years to solidify completely from its molten magma state beneath Earth's crust.
- 02
Granite's three essential minerals—feldspar, quartz, and mica—must each comprise at least 20 percent by volume for a rock to be classified as true granite.
- 01
The world's largest granite monolith, Stone Mountain in Georgia, rises 825 feet above ground and contains approximately 2.7 billion tons of rock.