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