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Transcript
Minerals
Minerals



Naturally occurring inorganic solids
consisting of one or more chemical elements
The atoms of these elements are arranged in
a systematic internal pattern, which creates a
a crystalline structure.
Minerals are the building blocks of rocks


Geologists spend a lot of time trying to
determine which minerals are in rocks.
Identifying what minerals are present is
based on each minerals unique set of
chemical and physical properties.
Colour


Not always reliable because colour can
be changed by the presence of
impurities in the mineral, by light, and
by weathering of the mineral’s surface.
Azurite is always blue, malachite is
always green.
Malachite
Azurite
Luster

How the mineral’s surface reflects light
(shiny, glassy, silky, pearly, etc.)

Galena has a
metallic luster
Streak



Color that is displayed when the mineral is
rubbed across a streak plate (more reliable
than just external color).
Streak color will not
always be the same
as the color of the
mineral.
Galena streaks gray;
Hematite streaks red.
Specific Gravity


A comparison of the weight of the
mineral to the weight of an equal
volume of water.
For example, gold has a specific gravity
of 19.3, which means that it weighs
19.3 times as much as an equal
volume of water.

Specific gravity can be used to distinguish
gold from pyrite (Fool’s Gold) which has a
specific gravity of only ~4.
Hardness

A mineral’s resistance to scratching

Measured using Mohs Hardness Scale
Mohs Hardness Scale
Increasing Hardness
Mineral
Hardness
Talc
1
Gypsum
2
Hardness of Some Common
Objects
Human fingernail (2.5)
Calcite
3
Copper penny (3.5)
Fluorite
4
Apatite
5
Glass (5-6)
Pocketknife blade (5-6)
Orthoclase (potassium feldspar)
6
Steel file (6.5)
Quartz
7
Topaz
8
Corundum
9
Diamond
10
Cleavage


The tendency to break consistently
along distinct planes.
Example, halite always forms cubes
Fracture


When minerals don’t cleave, they
fracture – break at random spots
Forms jagged, irregular surfaces.
Smell and Taste


Sulfur-containing minerals stink like
rotten eggs
Halite is salty tasting
Effervescence

Minerals containing carbonate, such as
calcite, will fizz when mixed with dilute
hydrochloric acid
Crystalline Form

The shape of the crystals the mineral
forms.