Stilbite Photo by  Patrick Laird ©

Physical Properties

Stilbite Photo by  Patrick Laird ©

HABIT

The habit of a mineral refers to the minerals external shape.  Free space and temperature are the two most important conditions in which minerals are allowed to grow.  Some minerals may only grow as a limited amount of habits while others may have several different habits.  There are two basic groupings of habits, single crystal and aggregate.  The first type of habits are related to single crystal formations.  The second type are aggregates which are many smaller crystals of the same mineral that make up one pattern or shape. (Amethyst Galleries, Inc.)  Listed below are some common types of habits and pictures to show what they look like.
 
 

Acicular - Natrolite Photo taken from Amethyst Galleries, Inc. ©	Bladed - Kyanite Photo taken from Amethyst Galleries, Inc. ©	Massive - Copper Photo by Patrick Laird ©
Compact - Opal Photo by Patrick Laird ©	Micaceous - Muscovite ESU Specimen Collection Photo by Patrick Laird ©	Fibrous - Ulexite Photo by Patrick Laird ©
Radiated - Wavellite Photo by Patrick Laird ©	Banded - Malachite Photo taken from Amethyst Galleries, Inc. ©	Stalactic - Aragonite ESU Specimen Collection Photo by Patrick Laird ©
Pisolitic - Bauxite ESU Specimen Collection Photo by Patrick Laird ©	Drusy - Vanadinite Photo by Patrick Laird ©	Botryoidal - Wavellite Photo by Patrick Laird ©
Geode - Quartz Photo taken from Amethyst Galleries, Inc. ©	Prismatic - Indocolite Photo taken from Amethyst Galleries, Inc. ©	Platy - Wulfenite Photo taken from Amethyst Galleries, Inc. ©

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CLEAVAGE AND FRACTURE

Cleavage is the tendency of minerals to break parallel to planes of atomic weakness.  The freshly cleaved area of a mineral will always be shiny, so that you can identify how many directions of cleavage it has.  This can help identify a mineral as minerals have distinct cleavage.  Basal cleavage is cleavage in one direction perpendicular to an axis.  Muscovite has basal cleavage.  Minerals that have one directional cleavage parallel to an axis is considered to be prismatic.  Gypsum is a mineral that has prismatic cleavage.  Minerals that have more than one direction of cleavage produce a geometric shape and that type of cleavage is named after the shape.  Halite has cubic cleavage, fluorite has octahedral cleavage, and calcite has rhombohedral cleavage. (Chesterman)

Fracture is the term given when a mineral breaks.  Fracture is different than cleavage because it doesn't happen parallel to planes of weakness.  Listed below are the five types of fracture. (Chesterman)

• Uneven - Uneven fracture is the result of irregular surfaces.
• Conchoidal - Also known as shell-like fracture.  This type of fracture has a smooth curving surface that looks like either broken glass or broken sea shells.
• Splintery - This type of fracture usually refers to fibrous minerals as they form elongated splinters.
• Hackly - A fracture that has a sharp jagged surface, usually in the metal class.
• Earthy - Refers to a surface that looks like broken clay or chalk.

SPECIAL PROPERTIES

There are a few properties that can help identify a small amount of minerals.

• Smell - some minerals have a distinct smell such as sulfur.
• Labradorescence - This term is applied to labradorite.  As you hold the specimen in your hand, move it back and forth so it will reflect light
• Taste - Halite will taste like salt, but it is very important that you have a general idea of what you are tasting as there are some minerals that are poisonous.  There are other minerals that have certain tastes either bitter, sweet, or salty.      DO NOT TASTE MINERALS THAT YOU DO NOT KNOW! 

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Created by Patrick Laird for GO336 Mineralogy at Emporia State University, November 11, 2002.

copyright 2002 Patrick Laird. All rights reserved.