GeoCE Module 3: Part 4 Flashcards
It refers to a mineral’s ability to transmit light.
Diaphaneity
TRUE OR FALSE:
All minerals are transparent.
FALSE
TRUE OR FALSE:
When minerals are thin, some distortion may occur, but light passes relatively freely through them.
FALSE
(when minerals are thick)
This mineral has been used in some industrial applications. Unfortunately , it is not very durable because it is very soft.
Iceland Spar / Calcite
Minerals that do not transmit light as well as clear calcite may be _________.
Translucent
Although it is not possible to see through them as with transparent minerals, if thin enough, these minerals transmit light.
Translucent Minerals
Minerals that are often commonly translucent.
calcite, gypsum, topaz, and many micas
This mineral comes in many different colors but, unless very finely crystallized, it is generally translucent to some degree.
Quartz
TRUE OR FALSE:
Some minerals are neither transparent nor translucent, and are opaque instead.
TRUE
These minerals do not transmit light unless the mineral is exceptionally thin.
Opaque Minerals
Most ________ minerals have metallic lusters and belong to the sulfide, oxide, or native element groups.
Opaque
What are the two more common examples of opaque minerals?
Pyrite and Magnetite
It is often used for quick identification of minerals.
Color
Sometimes, it can be diagnostic, but for many minerals it is ambiguous or even misleading.
Color
It is just one variety of the mineral corundum.
Ruby
They are different colored varieties of the same mineral.
Sapphires
TRUE OR FALSE:
The deep red color of rubies may seem distinctive.
TRUE
To add to the confusion, other minerals, such as ______ or _______, may have the same deep red color as ruby.
spinel or garnet
TRUE OR FALSE:
Color is ambiguous because many things can give a mineral its color.
TRUE
It is one of the most misunderstood mineral properties.
Color
TRUE OR FALSE:
When we see that a mineral has no color, what we are really observing is the color of the light that is being reflected or transmitted to our eye.
FALSE
(when we see that a mineral has color)
This light is called white light and it includes many different colors.
Normal light
When white light strikes a mineral surface, if all of the colors are reflected back to our eyes, the mineral will appear ______.
white
If none of the colors are reflected back to our eye, the mineral will appear ______.
black
TRUE OR FALSE:
If none of the colors are reflected back to our eye, the mineral will appear white.
FALSE
(the mineral will appear black)
TRUE OR FALSE:
When white light strikes a mineral surface, if all of the colors are reflected back to our eyes, the mineral will appear black.
FALSE
(the mineral will appear white)
The other ______________ are scattered in other directions or are absorbed or transmitted by the mineral in some way.
wavelengths of light
Although it would never occur to many people to check this mineral’s property, it is sometimes a key diagnostic
property.
Streak
It is not a useful property for identifying most silicates but is especially useful for distinguishing oxide and sulfide
minerals.
Streak
This property of a mineral is the color it has when finely powdered.
Streak
For mineral identification, it is much more reliable than mineral color, and it is easy to determine.
Streak
TRUE OR FALSE:
For mineral identification, color is much more reliable than mineral streak, and it is easy to determine.
FALSE (mineral streak is more reliable)
The usual method of determining this property of mineral is to rub the mineral against a ceramic streak plate or other piece of unglazed ceramic.
Streak
It is a good diagnostic property because the mineral is finely powdered, so structural and other nonchemical effects are minimized.
Streak color
This mineral comes in many different colors, but its streak is always white.
Calcite
This mineral is yellow but has a dark colored streak, as does chalcopyrite.
Pyrite (fool’s gold)
This minerals has a color similar to pyrite’s (in hand specimen), has a yellow-gold streak.
Gold
They routinely use streak when identifying minerals, both in the laboratory and in the field, but it cannot be determined for minerals harder than the hardness of a streak plate.
Mineralogists
TRUE OR FALSE:
Some minerals will emit light when they are activated by an energy form other than visible light
TRUE
Some minerals will emit light when they are activated by an energy form other than visible light. We call such an effect ____________.
luminescence
Examples of luminescence includes?
fluorescence, phosphorescence, and thermoluminescence
Fluorescence, phosphorescence, and thermoluminescence are example of?
luminescence
These minerals give off visible light when they are struck by energy of a shorter wavelength.
Fluorescent minerals
If the visible emission continues after the energy source is turned off, the mineral is _______________.
phosphorescent
What is an example of a phosphorescent mineral?
Pectolite
These minerals such as some tourmalines give off visible light in response to heating.
Thermolurminescent minerals
Some varieties of fluorite, calcite, and apatite also have this property.
Thermolurinescent
It is a form of light scattering due to very fine particles in the minerals or to textures of mineral surfaces
Play of Colors
This commonly appears when metallic minerals such as bomite tarnish or, in this case, when limonite tarnishes.
Play of Colors
It is a variety iridescence.
Labradorescence
What are the two special scattering effects most easily seen in gemmy polished minerals?
Chatoyancy and Asterism
A property sometimes visible in rubies, sapphires, garnets, and some other gems, refers to scattered light appearing as a ‘star.
Asterism
What is the famous sapphire that is in the American Museum of Natural History in New York.
Star of India
TRUE OR FALSE:
Chatoyancy and asterism are caused by closely packed parallel fibers or inclusions of other minerals within a mineral crystal.
TRUE
This famous sapphire has spectacular asterism.
Star of India
The color and shape of minerals are obvious to anyone, but ________ note other, more subtle, properties too.
mineralogists
It refers to a mineral’s toughness and its resistance to breaking or deformation.
Tenacity
TRUE OR FALSE:
Those that break, bend, or deform easily have great tenacity.
FALSE
(little tenacity)
TRUE OR FALSE:
Strong unbreakable minerals have little tenacity.
FALSE:
(strong tenacity)
Gemmy jade may be either of two minerals:
jadete or nephrite
It is a rock containing amphibole
Nephrite
It s one of the most tenacious natural materials known.
Jade
It does not easily break or deform, even when under extreme stress. That is one reason, besides beauty, that it is prized as a gemstone.
Jade
It is often leads to rigid, brittle minerals.
Ionic Bonding
It s an excellent example of a brittle mineral.
Halite
It is brittle, although the bonding in it is only about half ionic.
Quartz
TRUE OR FALSE:
Many metallic minerals, Such as native copper, are malleable, which mean we can shape them with a hammer.
TRUE
It is also ductile, which means we canstretch it out into wire like shapes.
Native Copper
Some minerals, including talc and chlorite, are flexible due to weak _______ and _________ holding well bonded layers of atoms together.
van der Waals
hydrogen bonds
TRUE OR FALSE:
When force is removed, slippage between layers allows bending.
FALSE
(when force is applied)
When _______ is released, minerals do not return to their original shape. S
pressure
TRUE OR FALSE:
Other minerals, notably the micas, are elastic.
TRUE
easily broken or powdered
Brittle
capable of being hammered into different shapes
Malleable
capable of being cut into shavings with a knife
Sectile
capable of being drawn into a wire-like shape
Ductile
capable of being bent into a different shape
Flexible
a bendable mineral that returns to its original shape after release
Elastic
It is a general term used to describe the way a mineral breaks or cracks.
Fracture
Terms used to describe fracture include even, ___________ and __________.
conchoidal and splintery
TRUE OR FALSE:
Because atomic arrangement is the same in all directions within a crystal, and chemical bonds are not all the same strength, most crystals break along preferred directions.
FALSE
What are the two important clues to crystal structure?
orientation and manner of breaking
It involves minerals breaking parallel to planes of atoms.
Cleavage
If the fractures are ______ and _______, we say that the mineral has good cleavage.
planar and smooth
What are the geometric terms we use to describe cleavage when appropriate?
cubic, octahedral, rhombohedral, or prismatic
Breaking to produce smooth planar surfaces (halite).
Even
Breaking to produce rough and irregular surfaces (rhodonite).
Uneven / Irregular
Fracturing to produce jagged surfaces and sharp edges (copper).
Hackly
Forming sharp splinters (kyanite, pectolite).
Splintery
Forming fibrous material (chrysotile, crocidolite).
Fibrous
Breaking with curved surfaces as in the manner of glass (quartz).
Conchoidal
What are the six (6) terms we used to describe fracture?
Even
Uneven / Irregular
Hackly
Splintery
Fibrous
Conchoidal
What are the five (5) terms we used to describe cleavage?
Basal
Cubic
Rhombohedral
Octahedral
Prismatic
well developed planar cleavage in one direction only; also sometimes called “platy” (micas)
Basal
Basal is sometime called _________.
Platy
three cleavages at 90 to each other (galena)
Cubic
three cleavages not at 9Þ to each other (calcite)
Rhombohedral
four cleavages that produce 8-sided cleavage fragments (fluorite)
Octahedral
multiple directions of good cleavage all parallel to one direction in the crystal (tremolite)
Prismatic
It is a mineral’s resistance to abrasion or scratching.
Hardness
It is determined by trying to scratch a surface of one mineral with an edge or corner of a second mineral.
Relative hardness
It’s symbolized by H.
Relative hardness
TRUE OR FALSE:
If a scratch or abrasion results, the first mineral is the harder.
FALSE
(softer)
It is not quite the same as relative hardness.
Absolute hardness
It is the measure of a material’s ability to resist permanent deformation.
Absolute hardness
TRUE OR FALSE:
Although rarely done by mineralogists, values of absolute hardness may be determined in several ways; the easiest is to use an indenting tool similar to ones used to measure the hardness of steel.
TRUE
It measures the force necessary to produce a permanent indentation in a flat surface.
Indenting tool
This table gives the relative hardness scale that is used by mineralogists.
Mohs Hardness Scale
This table was named after the Austrian mineralogist Friedrich Mohs who developed it in 1812.
Mohs Hardness Scale
He is an Austrian mineralogist who developed the Mohs Hardness Scale.
Friedrich Mohs
It ranks minerals by their ability to scratch each other.
Mohs Scale
It is related to absolute hardness but does not measure the same thing because resistance to Scratching depends on additional factors.
Mohs Scale
It is not linear and is close to being exponential.
Mohs Scale
TRUE OR FALSE:
If we compare the absolute hardness with Mohs hardness scale, we find that the absolute hardness is not linear and is close to being exponential.
FALSE(Mohs Hardness scales is the one close to being exponential)
What are the four (4) hardest minerals?
quartz, topaz, corundum, diamond
This mineral is only slightly harder than talc.
Gypsum
This mineral has a hardness five times greater than corundum.
Diamond
TRUE OR FALSE:
We can estimate relative hardness by conducting scratch tests to compare the hardness of an unknown mineral to the minerals in the Mohs hardness Scale.
TRUE
We can estimate relative hardness by conducting these tests to compare the hardness of an unknown mineral to the minerals in the Mohs hardness Scale.
Scratch test
Alternatively, we can approximate hardness by comparing mineral hardness with the hardness of a ___________, _________, ___________, ______, or several other common objects
fingernail, penny, pocketknife, glass
It id one of the softest minerals known, and has a hardness of 2 on the Mohs hardness scale.
Gypsum
This minerals has a hardness of 1 on the Mohs hardness scale.
Talc
This minerals has a hardness of 3 on the Mohs hardness scale.
Calcite
This minerals has a hardness of 4 on the Mohs hardness scale.
Fluorite
This minerals has a hardness of 5 on the Mohs hardness scale.
Apatite
This minerals has a hardness of 6 on the Mohs hardness scale.
Feldspar
This minerals has a hardness of 7 on the Mohs hardness scale.
Quartz
This minerals has a hardness of 8 on the Mohs hardness scale.
Topaz
This minerals has a hardness of 9 on the Mohs hardness scale.
Corundum
This minerals has a hardness of 10 on the Mohs hardness scale.
Diamond
These tests are often straightforward, but there can be complications.
Scratch test
TRUE OR FALSE:
Mineral specimens may be too small or too valuable to scratch
TRUE
They may consist of many grains loosely cemented together so that scratch tests are not possible.
Large samples
The results of these tests may be ambiguous, especially if two minerals have the same, or nearly the same. hardness.
Scratch tests
TRUE OR FALSE:
The results of scratch tests may be ambiguous, especially if two minerals have the same, or nearly the same hardness.
TRUE
