RocksdayRocksday #6 · October 27, 2026
The answer was Marble
Limestone recrystallized by heat and pressure into a mosaic of interlocking calcite grains.
The clues
- Type
- Metamorphic rock
- Color & luster
- White, Gray, Pink, Green · Sugary sparkle
- Mohs hardness
- 3–4
- Texture
- Interlocking crystals (non-foliated)
- Found in
- Carrara, Italy; Yule, Colorado
How to recognize marble
- Sparkly, sugary crystals on broken surfaces.
- Fizzes in acid.
- A knife scratches it.
- Often swirled or veined.
Did you know? Michelangelo's David is carved from Carrara marble; the Lincoln Memorial is Colorado Yule marble.