Waco Gem and Mineral Club, Waco, Tx

12.1 Gold as a Mineral


12.1: Gold as a mineral

Gold is a popular mineral, and you‘ll be able to find any number of books about it in a bookstore or at your local library to recommend to your juniors for learning about gold as a mineral. One example from my own home library is Joseph Petralia‘s Gold! Gold! A Beginner’s Handbook & Recreational Guide. Also the U.S. Geological Survey distributes a free pamphlet written by Harold Kirkemo, William L. Newman, and Roger P. Ashley and entitled simply Gold.

Or direct kids to a general rock and mineral identification book, such as:

Pellant, The Complete Book of Rocks & Minerals

Zim & Shaffer, Rocks & Minerals: A Golden Guide

Fuller, Pockets Rocks & Minerals

Simon & Schuster‘s Guide to Rocks & Minerals

Pough, Rocks & Minerals: Peterson Field Guide

Chesterman, National Audubon Society Field Guide to North American Rocks & Minerals

A neat little book especially suitable for younger kids is Darryl Powell‘s Gold! A Coloring and Activity Book for Young Prospectors. In it, Nugget the Gold Prospector tells kids where gold is found, what it looks like, and why it‘s so valuable, all with large-format illustrations for kids to color and a quiz, crossword puzzle, and other activities at the end. You can get copies and current pricing by contacting Diamond Dan Publications, c/o Darryl Powell, (585) 278-3047.

Here‘s how gold compares to iron pyrite by a variety of common mineral properties:

Property Gold Pyrite
 Color Golden-Yellow  Brassy-Yellow 
 Streak  Gold-Yellow  Greenish-Black
 Cleavage  None  Cubic & Octahedral
 Fracture  Hackly  Uneven
 Luster  Metallic  Metallic
 Hardness  2.5 - 3.0  6.0 - 6.5
 Crystal Shape  Isometric / Cubic  Isometric / Cubic
 Specific Gravity  15.6 - 19.3  4.9 - 5.2

Gold is one of the basic elements in chemistry: atomic number 79. In the periodic table, it‘s listed as Au, from the Latin word for gold, aurum. It‘s a 'noble' metal, meaning it doesn‘t oxidize under normal conditions. By contrast, iron pyrite is a compound (iron disulfide, or FeS2) made from the elements iron and sulfur. In the air, pyrite tends to decompose over time, reacting with oxygen and water to form sulfuric acid. While gold has many uses (see Earth Resources: Minerals in the Home Activity 2.2), pyrite has just a few, such as the manufacture of sulfuric acid and sulfur dioxide, as an aid in the recovery of other metals (iron, gold, copper, cobalt, nickel, etc.), or to make inexpensive costume jewelry.