Download - Minerals Patterns in Nature
MINERALSPATTERNS IN NATURE
CMUBill PalmerLecture 4
Central Methodist University
What are Minerals? Natural Chemically Pure Make up “rocks” Solid Inorganic Often form
crystals Crystal structure
is organized arrangement of atoms
How Rocks and Minerals Different?
ROCKS ARE COMPOSED OF
MINERALS
MINERALS ARE CHEMICALLY
PURE
Big important hint: Learn the Minerals and the Rocks will be easy to learn!!
Your Very Life Depends on Minerals
General Facts about Minerals Between 2 - 3,000 have been identified A few are “native elements” -- made of only one
element, such as sulfur, gold. copper, and graphite (carbon)
Most are compounds, especially the silicate group (Si, O)
Other important groups are oxides, carbonates, and sulfides
About a dozen are common in most rocks
Quartz Feldspar (group) Muscovite (white
mica) Biotite (black
mica) Calcite Pyroxene
Olivine Amphibole
(group) Magnetite,
limonite, and other iron oxides
Pyrite Galena Barite
Common Uses Include:
Aluminum--packaging, transport, building Beryllium--gemstones, fluorescent lights Copper--electric cables, wires, switches Feldspar--glass and ceramics Iron--buildings, automobiles, magnets Calcite--toothpaste, construction
Minerals are identified by their key characteristics
Hardness Crystal shape
(form) Luster Color Streak
Cleavage/fracture Density (specific
gravity) Special properties
--reaction to acid --fluorescence --salty taste --magnetismLearn how to test minerals
for these characteristics instead of trying to memorize
each mineral!!With 3,000 different minerals it
would be next to impossible to learn all the names!!
Mineral Hardness Ability to scratch
another mineral Mohs scale from
1 (talc) to 10 (diamond)
Quartz (most common mineral and most dust particles) is 7
Mineral HardnessHARDNESS OF SOME COMMON ITEMS: MOH’S SCALE
2.5 Fingernail 2.5–3 Gold, Silver 3 Copper Penny 4-4.5 Platinum 4-5 Iron 5.5 Knife Blade 6-7 Glass 6.5 Iron Pyrite 7+ Hardened Steel
File
1 Talc Talcum powder. 2 Gypsum Plaster of Paris.
Gypsum is formed when seawater evaporates from the Earth’s surface.
3 Calcite Limestone and most shells contain calcite.
4 Fluorite Fluorine in fluorite prevents tooth decay.
5 Apatite When you are hungry you have a big "appetite".
6 Orthoclase Feldspar In German, "feld" means "field".
7 Quartz Found everywhere. 8 Topaz The November
birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8.
9 Corundum Sapphire and ruby are varieties of corundum. Twice as hard as topaz.
10 Diamond Used in jewelry and cutting tools. Four times as hard as corundum.
Crystal Shape (Form) External structure
due to internal arrangement of the atoms
Six basic groups of shapes, with about three dozen variations
Luster Describes how
light reflects off the surface
Main categories are “metallic” and “non-metallic”
Non-metallic dull glassy waxy pearly
Color Results from ability to absorb some wavelengths and reflect others
Some minerals have characteristics colors
Others vary due to chemical differences or impurities (atoms mixed inside the main elements)
COLOR is usually the worst way to identify a mineral.
Streak Color of the powder
when rubbed on a “streak plate” (unglazed porcelain)
May be same as hand-specimen or different
Some paint is based on powdered minerals (streaks)
Mineral cleavage/fracture Some minerals split along flat surfaces
when struck hard--this is called mineral cleavage
Other minerals break unevenly along rough or curved surfaces--this is called fracture
A few minerals have both cleavage and fracture
Due to how the atoms are arrangedBe sure you understand the difference between
CLEAVAGE and FRACTURE.
Density (Specific Gravity) All minerals have density
(mass / volume), but some are very dense
Examples include galena, magnetite, and gold
Specific Gravity is the density of the mineral compared with density of water
Remember our Lab? Some minerals just feel
“heavy”
Special Characteristics--the “Acid Test”
Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas)
Special Characteristics-- Fluorescence
Some minerals will glow when placed under short-wave or long-wave ultraviolet rays
Franklin and Ogdensburg NJ are famous for their fluorescent minerals
Special Characteristics--Salty Taste
DO NOT TASTE MOST MINERALS!
Halite is the exception--it will taste salty
Kaolinite (clay) will stick to your tongue
Special Characteristics--Magnetism
Many iron minerals will produce an invisible magnetic force field
“Lodestone” was used by Vikings more than 1,000 years ago as compassesMagnetite
A detailed look at some common minerals
OrSome common minerals that make-up most
rocks and some minerals your kids may ask you what they are and you will want to know so you
can impress them.
Quartz Very hard 7.0 Many, Many forms
Clear Rosy=pink Milky=white Smoky=black Chalcedony=multicolor Agate=color rings Chert=white, brown, tan (very common) Mozarkite=pink/purple bands (MO State Rock) Amethyst=purple Jasper=dark blood red
QuartzWhich is which?
QuartzWhich is which?
Amethyst
Mozarkite
Agate
Rosy QuartzChert
Jasper
Smoky
Milky Chalcedony
Clear
Feldspar Hard 6.0 Vitreous, pearly Good Cleavage,
breaks at 900
Plagioclase Sodium Calcium Aluminum
silicate White, Yellow, Pink Striations Orthoclase
Potassium Aluminum Silicate
White, yellow, pink NO Striations
How to Identify Feldspars
pink dark
Check the Color
light
Check for
Striations
ORTHOCLASE FELDSPAR
PLAGIOCLASEFELDSPAR
yes no
Mica Soft 2.5-3.0 “Saran Wrap” Breaks in thin
layers Biotite
Dark Muscovite
Clear
Calcite Soft 3.0 Excellent
cleavage in 3 directions NOT 900 Colorless White
Yellowish
Rhombohedrons
Pyroxene Hard 5.5-6.0 “Augite” Dark Green to
Gray Eight-sided
prisms
Olivine Hard 7.0 White Streak Pale to dark olive
Green Peridot is the
Gemstone
Amphibole Hard 5.5 White to gray
Streak Dark gray to
black
MagnetiteHematite, Limonite
Iron Oxides Iron Ores Color Varies with
amount of Iron Limonite = yellow Hematite =
reddish Magnetite =
black Tell apart by
streak
Pyrite Hard 6.0-6.5 Dark gray Streak Brassy yellow “Fool’s Gold”
Galena Soft 2.5 Silver Gray Metallic Perfect Cubes MO State Mineral Source of Lead
Barite Soft 3.0-3.5 White, but can
be stained reddish with iron
Heavy “Tiff” of S MO
Wrap-ups 1. Research the common uses for the 12
common minerals in the lecture. 2. List the diagnostic characteristics of
minerals and include some of the possible variations.
3. What is the difference between a rock and a mineral?
4. Define a mineral. 5. What Moh’s Scale and what are some
hardness of some common objects.
Wrap-ups 6. What is a crystal? Do all minerals form
crystals? What causes a crystal? 7. What is luster? What are the main
types? 8. Distinguish between cleavage and
fracture. 9. Why is color a poor distinguishing
characteristic when identifying minerals? 10. What is the Missouri State Mineral?
Useful Web Sites www.mii.org www.mineral.galleries.com/mine
rals www.mineral.net www.usgs.gov