WELCOME TO THE GLENDALE COMMUNITY COLLEGE presented by: Susan Celestian - Curator of the Arizona Mining and Mineral Museum Stan Celestian - Photographer

WELCOME TO THE GLENDALE COMMUNITY

COLLEGE

presented by:

Susan Celestian - Curator of the Arizona Mining and Mineral Museum

Stan Celestian - Photographer

MINERAL IDENTIFICATIONPROGRAM

© copyright 2002

Crystals………………………………….…4 Isometric……………………………….…..6Hexagonal……………………………….…10Tetragonal………………………………….14Orthorhombic…………………………..….18Monoclinic………………………………...23Triclinic……………………………………26Resources………………………………….29

TABLE OF CONTENTS

This is the second part of Mineral Identification Program

Introduction to Mineral Identification Basics

Welcome to the fascinating world Welcome to the fascinating world of Minerals. The purpose of this of Minerals. The purpose of this

CD is to present you with some of CD is to present you with some of the basic techniques used to the basic techniques used to

identify minerals.identify minerals. This Power Point Presentation can also be viewed in the “edit” mode. Here you can view the many notes associated with the slides.

Mineral Identification Basics PHYSICAL PROPERTIES CRYSTALS

A CRYSTAL is the outward form of the internal structure of the mineral.

The 6 basic crystal systems are:

ISOMETRICHEXAGONAL

TETRAGONALORTHORHOMBIC

MONOCLINICTRICLINICDrusy Quartz on Barite

Mineral Identification Basics PHYSICAL PROPERTIES CRYSTALS

CRYSTAL SYSTEMS are divided into 6 main groups.

ISOMETRIC - Fluorite Crystals

The first group is the ISOMETRIC. This literally means “equal measure” and refers to the equal size of the crystal axes.

Mineral Identification Basics ISOMETRIC CRYSTALS

ISOMETRICIn this crystal system there are 3 axes. Each has the same length (as indicated by the same letter “a”).

They all meet at mutual 90o angles in the center of the crystal.

Crystals in this system are typically blocky or ball-like.ISOMETRIC

Basic Cube

a3

a2

a1


ISOMETRIC Crystal Model

Within this ISOMETRIC crystal model is the OCTAHEDRAL crystal form (yellow) and the TETRAHEDRAL crystal form (shown by the black lines).


ISOMETRIC - Basic Cube

a1

a3

a2

a3

a2

a1

Fluorite cube with crystal axes.

Mineral Identification Basics ISOMETRIC BASIC CRYSTAL SHAPES

Octahedron

Spinel

Cube

Fluorite Pyrite

Cube with Pyritohedron

Striations

TrapezohedronGarnetGarnet Garnet - Dodecahedron

Mineral Identification Basics HEXAGONAL CRYSTALS

HEXAGONAL - Three horizontal axes meeting at angles of 120o and one perpendicular axis.

a1

a2

a3

HEXAGONAL Crystal Axes

c


HEXAGONAL Crystal Model

HEXAGONAL

This model represents a hexagonal PRISM (the outside hexagon - six sided shape). The top and bottom faces are called PINACOIDS and are perpendicular to the vertical “c” axis.

Within this model is the SCALENOHEDRAL form. Each face is a scalenohedron. Calcite often crystallizes with this form.


These hexagonal CALCITE crystals nicely show the six sided prisms as well as the basal pinacoid.


RHOMBOHEDRON

Dolomite

SCALENOHEDRON

Rhodochrosite

QuartzHanksite

Pyramid Pyramid FaceFace

Prism Prism FacesFaces

Prism Prism FacesFaces

Pyramid Pyramid FacesFaces

Vanadinite

Mineral Identification Basics TETRAGONAL CRYSTALS

TETRAGONAL

Two equal, horizontal, mutually perpendicular axes (a1, a2)

Vertical axis (c) is perpendicular to the horizontal axes and is of a different length.

TETRAGONAL Crystal Axes

a1a2

c

c

a2a1

This is an Alternative Crystal Axes


TETRAGONAL Crystal Model

TETRAGONAL

This model shows a tetragonal PRISM enclosing a DIPYRAMID.


WULFENITE

Same crystal seen edge on.Same crystal seen edge on.


APOPHYLLITE on Stilbite

This is the same Apophyllite crystal looking down the “c” axis.

The red square shows the position of the pinacoid (perpendicular to the “c” axis).

Mineral Identification Basics ORTHORHOMBIC CRYSTALS

ORTHORHOMBIC

Three mutually perpendicular axes of different lengths.

ORTHORHMOBIC Crystal Axes

ab

c

a

c

b

An Alternative Crystal Axes Orientation


ORTHORHMOBIC Crystal Model

ORTHORHOMBIC

This model shows the alternative axes where the vertical “c” axis is not the longest axis.

The model shows the outside “brick” shape of the PRISM and the inner shape is a DIPYRAMID. The top and bottom faces are called PINACOIDS and are perpendicular to the “c” axis.


Topaz from Topaz Mountain, Utah.


BARITE is also orthorhombic. The view above is looking down the “c” axis of the crystal.


STAUROLITE

Prism View

Pinacoid

View


This is a Staurolite TWIN with garnets attached.

Mineral Identification Basics MONOCLINIC CRYSTALS

MONOCLINIC

In this crystal form the axes are of unequal length.

Axes a and b are perpendicular.

Axes b and c are perpendicular.

But a and c make some oblique angle and with each other.

MONOCLINIC Crystal Axes

a

b

c


MONOCLINIC Crystal Model

MONOCLINIC

In this model the outside shape is the PRISM. It looks like a distorted brick - flattened out of shape.

Inside is the DIPYRAMID.


Gypsum Mica

Orthoclase

Top View

Mineral Identification Basics TRICLINIC CRYSTALS

TRICLINIC

In this system, all of the axes are of different lengths and none are perpendicular to any of the others.

TRICLINIC Crystal Axes

a b

c


TRICLINIC Crystal Model

TRICLINIC

Again in this model the outside shape is the PRISM.

Located within the prism is the DIPYRAMID.


Microcline, variety Amazonite

Mineral IdentificationMineral Identification RESOURCESRESOURCES

http://www.gc.maricopa.edu/earthsci/imagearchive/index.htm

For lots of useful images of minerals and more facts about minerals, check out this web site:

This copyrighted Power Point CD was produced strictly for educational purposes. Any attempt at using the images within this program for monetary gain is illegal. The authors have given permission to use the program or parts of it, provided credit is given to the Arizona Mining and Mineral Museum, its Curator - Susan Celestian and the photographer - Stan Celestian.

THE

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WELCOME TO THE GLENDALE COMMUNITY COLLEGE presented by: Susan Celestian - Curator of the Arizona Mining and Mineral Museum Stan Celestian - Photographer