Vintage First Issue 1992 Minerals 29c Postal Stamps Philately Lot of 4

Vintage First Issue 1992 Minerals 29c Collectible US Postal Stamps - Collectable Postage Collecting- Philately - Lot of 4 The United States is rich in mineral deposits. Four are featured on the Minerals commemorative stamps. Copper occurs naturally in large masses and has long been used by man. Malleable and easily worked with, copper conducts heat and electricity and resists corrosion. Azurite, a semiprecious stone, is used mainly for ornamental purposes. Variscite, found in many shades of green, is often used as a substitute for turquoise. Wulfenite crystals, generally a brilliant yellow or orange-red, can be found as large as 2 inches.