Geology of Gems

Geology of Gems

Course Overview

Welcome to the Geology of Gems on-line course guide! This course is an introduction to both to origin and occurrence of gems and precious materials commonly used in jewelry and art. Gems, precious stones, metals, and other valuable commodities come from the Earth; most are associated with mineral ore deposits formed long ago, but how these deposits form can be seen in many geologic settings forming today. The study of gems and precious materials in the context of how they form help to explain where they are known to occur or might be found (through prospecting and exploration). This information is also useful to create synthetic gem materials through chemical, physical, and even biological methods for a variety of purposes beyond its use in art and jewelry.

Eleven "chapters" and six laboratory class exercises cover content and activities equivalent to a 3-4 credit semester introductory science course suitable for in undergraduate college credit.

The final component (Chapter 11) of the course is an evaluation of gemstone resources of regions of the United States and around the world: where they occur, how they are acquired, and what they occur with? Students will choose selected gemstone and explore scientific and natural occurrences, and the regional environmental, soclal, economic, and political impacts associated with mining retrieval and manufacturing of gem resources.

Course Notes and Laboratory Exercises

  Chapter 1 - What Are Gems & Minerals?
Chapter 2 - Physical Properties of Gems
Chapter 3 - Basic Geologic Principals
Chapter 4 - Structure of the Earth
Chapter 5 - Igneous Rocks and Processes
Chapter 6 - Gems of Igneous Origin
Chapter 7 - Sedimentary Deposits and Rocks
Chapter 8 - Gems of Sedimentary Origin
Chapter 9 - Metamorphic Rocks and Processes
Chapter 10 - Gems From Metamorphic Rocks
Chapter 11 - Gem Resources of the World

Lab 1 - Mineral Identification
Lab 2 - Physical Properties of Gems
Lab 3 - Gems From Igneous Rocks
Lab 4 - Gems From Sedimentary Rocks
Lab 5 - Gems From Metamorphic Rocks
Lab 6 - Geologic Maps and Principles
See examples of Gems and Precious Stones

Selected resources about gems and precious stones.


What are Gems and Precious Stones?

The word "gem" has a variety of linguistic uses, however most dictionaries basically define "gem" (as a noun) as a crystalline substance that can be cut and polished for jewelry or adornment. As an adjective, the word "gem" implies "something of quality or appeal, applied to found and treasured objects, even people." However, for our purposes, the word gem applies to a mineral in crystalline form. The term precious stone applies to other materials of natural origin including minerals (in complex crystalline aggregates, or in amorphous forms), but also include "rock" like agate or obsidian, and substances of "organic" origin, such as jet, pearls, or amber. The word gemstone may apply to crystalline gems, but by name includes other materials including precious stones. However, gems (gemstones) and precious stones can include both "natural stone" and synthetic or imitation materials.

The words gem and gemstone imply some sense of "economic and aesthetic value"—which is not always true! Not all gemstone materials fall into the class of jewelry-grade stones (like precious diamonds, emeralds, sapphires, and rubies). For instance, most diamonds mined are not "gem quality" and are sold and used for industrial purposes. And, although garnet is used as a gemstone, the vast majority of it mined to produce emery powder (such as the grit glued to sandpaper). Synthetic gemstones range in quality (and price) from higher-end cubic zirconium, rubies, and even diamond to low-end materials created from glass and even plastic. However, high-end quality gems sold in stores like Tiffany's are from "natural" and "legal" sources. However, buyer beware! Even "high quality" synthetics can be difficult to distinguished from natural gemstones by professional jewelers.
Click on images for a larger view throughout this website.
Precious gemstones
Precious gemstones
The Rock Cycle
The Rock Cycle
Alternate Laboratory assignments (.pdf format)
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6 (worksheet)
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Note that the labs listed above are revised versions of these older laboratory assignment in .pdf format and have revised color graphics.
NSF logo
PI/co-PI(s): Roland Scal, Phil Stoffer, Vazgen Shekoyan

"This material is based upon work supported by the National Science Foundation under Grant Number (NSF Grant Number: 1044769)"

"Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."