Mineral Identification

Anticipation Guide #2 1) Rocks cannot be made of organic

material 2) Luster is classified as metallic and

non-metallic 3) Scientist use tests to identify

minerals 4) Minerals that make up rocks can

be mined as ores 5) A liquid or gas can be classified as

a mineral

VA SOL

ES 4 The student will investigate and understand how to identify major rock-forming and ore minerals based on physical and chemical properties. Key concepts include a. properties including hardness,

color and streak, luster, cleavage, fracture, and unique properties; and.

Objective

3 Define chemical and physical properties of minerals to include luster, hardness, cleavage, fracture, streak, color, specific gravity, and special traits.

Enduring Understanding

Minerals are the building blocks of rocks.

Mineral Identification

With more than 3,000 minerals in Earth’s crust how does one go about identifying an unknown mineral?

Mineral Identification Geologists rely on several simple tests

that are based on a mineral’s physical and chemical properties. It is usually best to use a combination of tests rather than just one to identify minerals

Mineral Properties Color is one of the most noticeable but

least reliable characteristics

Mineral Properties

Sometimes caused by the presence of trace elements or compounds

Mineral Properties Streak is the color of the mineral when it

is broken up into a powder and is a much more reliable identification method because it rarely changes

Both of these samples are hematite; both have a reddish-brown streak

Mineral Properties Streak is easily determined by rubbing

the mineral across an unglazed porcelain plate

Mineral Properties Streak is used to distinguish pyrite from

gold

Mineral Properties

Streak is used to distinguish pyrite from gold

Mineral Properties Luster is the way a mineral reflects light

from its surface and is caused by differences in mineral chemical compositions

Mineral Properties

Either metallic or nonmetallic (dull, pearly, waxy, silky)

Mineral Properties Texture describes how a mineral feels to

the touch Rough, smooth, ragged, greasy, soapy,

glassy

Mineral Properties Hardness is a measure of how easily a

mineral can be scratched and is determined by the arrangement of it’s atoms.

Mineral Properties The Mohs hardness scale is used to

compare a sample to the hardness of ten known minerals

Mineral Properties Cleavage determines whether a mineral

will split easily and evenly along one or more flat planes

Mineral Properties Mica has perfect cleavage in one

direction

Halite has cubic cleavage (3 planes)

Mineral Properties Fracture means the mineral is tightly

bonded and breaks with rough or jagged edges Quartz has fracture

Mineral Properties Specific Gravity compares the weight of

the mineral to an equal volume of water at 4 degrees C

Mineral Properties Special Properties such as light

reflection and reactions to acids are also useful tools

Mineral Properties Calcite fizzles when in contact with

HCl

Mineral Properties Calcite also can cause double images

Mineral Properties Magnetite will attract iron

Mineral Properties Sulfur produces a rotten egg odor