Boy Scouts of America Merit Badge Series: Geology GIA JUNIOR GEMOLOGIST PROGRAM ™

GEOLOGY AND GEMS Geology is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it.

A rock is a solid material made up of minerals Rocks are the building blocks that make up the earth Rocks tell a story about the earth and how it was formed WHAT IS ROCK?

Igneous rocks start out in a molten or semi-molten state and become solid when they cool. Pumice IGNEOUS ROCK Eruption of Mount St. Helens volcano,1980

extrusive intrusive IGNEOUS ROCK FORMATION

Granite Lava IGNEOUS ROCKS

Sedimentary rocks are formed by layers of sediments squeezed and pressed together over a long period of time. Sandstone SEDIMENTARY ROCK

CONVICT LAKE, CALIFORNIA Metamorphic rocks have their makeup, texture, or structure changed by great heat, pressure, or both. Slate METAMORPHIC ROCK

MOUNT CHO OYU, NEPAL (26,906 ft.) Marble with spinel METAMORPHIC

DEFORMATION OF ROCKS Rocks are continually being subjected to forces that bend them. A fold can be defined as a bend in rock that is the response to compressional forces. Folds are most visible in rocks that contain layering.

ROCK ACTIVITY

CAREERS IN GEOLOGY What is someone called who studies geology?  A geologist What does a geologist do?  They work to understand the history of our planet so that they can foresee how past events might influence the future.

ADVANCED CAREERS IN GEOLOGY Paleontology Mineralogy Volcanology Hydrology

Mineralogy is the science that involves the chemistry, crystal structure, and physical (including optical) properties of minerals and the processes that create them. MINERALOGY

MINERALS To be considered a mineral a material must have all of the following features: Solid Inorganic Formed in Nature Specific Chemical Composition Crystal Structure

CRYSTAL STRUCTURE IDENTIFICATION OF MINERALS

The most exciting aspects of minerals are their beautiful and elegant crystal forms. A mineral’s crystal form is an exterior expression of what is happening on the inside of a mineral at the atomic level. CRYSTAL STRUCTURE

CRYSTAL STRUCTURE ACTIVITY

Harder Softer 140x 124,000x Diamond Corundum (Sapphire/Ruby) Topaz Quartz Orthoclase feldspar Apatite Fluorite Calcite Gypsum Talc MOHS HARDNESS SCALE

IDENTIFICATION OF MINERALS SPECIFIC GRAVITY The ratio of the weight of a material to the weight of an equal volume of water Each square is the same size, but each has progressively more dots The more dots the denser the square The denser the material the more it weighs

What color is sunlight/white light?  All the colors in a rainbow When light hits an object, some of the colors get absorbed Other colors reflect within the object and transmit back to our eyes This is the color we see IDENTIFICATION OF MINERALS HOW DO MINERALS GET THEIR COLOR?

COLOR ACTIVITY

Streak testing is a method used in mineral identification Helps distinguish gold (yellow streak) from pyrite (black streak) Streak testing is destructive and not recommended IDENTIFICATION OF MINERALS STREAK

IDENTIFICATION OF MINERALS LUSTER Luster is a way that light interacts with the surface of a material High-luster Categories  Adamantine - diamond like  Metallic Medium-luster Categories  Vitreous - glass like Low-luster Categories  Waxy – Dim and blurred like the surface of a candle

LUSTER ACTIVITY

Gemology is the science, art and profession of identifying and evaluating gemstones. It may be considered a branch of mineralogy. GEMOLOGY

WHAT IS A GEM? Beautiful Rare Durable

GEMSTONE FAMILIES Group A family of gems from several closely related mineral species Species A broad gem category based on chemical composition and crystal structure Variety A subcategory of species, based on color, transparency, or phenomena (an optical effect, like a star in star sapphire, or the blue sheen in moonstone)

Inclusions can be a variety of objects enclosed within a gemstone or those that extend into it from the surface. Inclusions can be: Other minerals Gas Liquid INCLUSIONS “Lily-pad” inclusion in a peridot Three-phase inclusion in an emerald

Inclusions can also be found in organic material: Leaves Bugs such as termites, mosquitoes, or ants Tree bark INCLUSIONS IN ORGANIC MATERIAL

Some gems display special effects when they interact with light. These stones are called phenomenal gems because they display unusual optical effects. PHENOMENA

INCLUSION ACTIVITY

CAREERS IN GEMOLOGY

COMMERCIAL USES FOR ROCKS AND MINERALS

USES FOR IGNEOUS ROCKS

USES FOR SEDIMENTARY ROCKS

USES FOR METAMORPHIC ROCKS

INDUSTRIAL AND COMMERCIAL MINERAL USE

Photo credits: Joel Beeson Richard D. Fisher Chuck Fryer Tino Hammid, Gary Hill Tory Kooyman Pacific Studios, Newport, Oregon Valerie Power Maha Tannous Parke D. Snavely, Jr. of the USGS Eric Welch Robert Weldon