Related Clues:

• Sedimentary rock
• Building material
• Sound quality for George?
• Grand Canyon material
• S with S, by the sound of it? That's a hard one
• The hard sound of S with S?
• It's hard to get the gritty sound of this
• Common sedimentary rock
• Rainbow Bridge National Monument, essentially
• Construction rock
• Such building material sets, and no mistake!
• Among the best of building materials, one stands out
• Rock fans nod assent
• Zion National Park material
• Rock formed of compacted and hardened grains