<ul><li>Gems, Minerals</li><li>Amethyst</li><li>Rhodochrosite</li><li>Tourmaline</li><li>Petrified Wood</li></ul><br><br>On June 3, 1974, in Lincoln, ND. the US Post Office Dept issued this Se-Tenant of four stamps, depicting Gems and Minerals of the United States Mineral Heritage. This was the first US stamps series designed by rotating the block 45 degrees to create a diamond effect. Included here are the Amethyst, Rhodochrosite, Tourmaline and Petrified Wood.

GEMS ~ MINERAL HERITAGE ~ AMETHYST ~ RHODOCHROSITE ~ TOURMALINE ~ PETRIFIED WOOD #1541a Block of 8 x 10¢ US Postage Stamps