Related Clues:

• Mined rocks
• Zincite, e.g.
• Ubiquitous ore
• "Buried" treasure found in 17-, 27-, 44- and 59-Across
• Bauxite, for example
• It may be pumped
• Gate material
• Healthful intake
• Metal-in-the-rough
• Golf-shop buy
• Frequently pumped item
• Strong metal
• Nickel in a pocket?
• Notable curtain material?
• Mined stuff