Lesson 4.1 Flashcards by Kage Lance San Pedro

a naturally occurring, inorganic,
homogeneous solid, with a definite
chemical composition, and an ordered
crystalline structure.

Minerals

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Physical Properties of Minerals

Color
Streak
Luster
Crystal habit
Cleavage
Fracture
Hardness
Specific gravity

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refers to certain wavelengths of light that are reflected by a
mineral and is perceived by the observer.

Color

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is the color of the powdered form of a mineral.

Streak

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is the appearance of a mineral’s surface and is dependent on
how it reflects light.

Luster

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–is the characteristic shape in which a mineral grows
and is a projection of the mineral’s crystal structure.

Crystal habit

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is the tendency of some minerals to break along flat
surfaces.

Cleavage

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is the pattern in which the mineral breaks aside from its
planes of cleavage.

Fracture

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is the resistance of the minerals to scratching.

Hardness

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is the ratio of a minerals’ weight to the weight of an
equal volume of water.

Specific gravity

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Chemical Properties of Minerals

Solubility
Melting point

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refers the ability of a substance to dissolve in a solvent at a
specified temperature.

Solubility

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refers to the temperature at which solid turns into liquid.

Melting point

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Mineral Groups Based on Chemical Composition

elements
sulfides
halides
oxides and hydroxides
nitates, carbonates, borates
sulfates
chromates,molybdate,tungstates
phosphates, arsenates, vanadates
silicates

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Most of the minerals here are composed of only one _.
Having knowledge about elements enables scientists to identify
bonding possibilities and compounds that can be created.

element

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Minerals under these group are composed of a metal joined by
a sulfur. Metallic luster is the characteristic that distinguish
them.

Sulfides

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These are nonmetal groups which consists of chlorine,
ﬂuorine, bromine, and iodine as their main chemical
constituent.

Halides

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These are mineral groups composed of one or more metals
joined with oxygen, water, or hydroxyl (OH–)

Oxides and
hydroxides

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It is formed when a metal is combined with carbon, nitrogen
and boron.

Nitrates,
carbonates,
borates

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One or more metal is combined with a sulfate compound (SO4)

Sulfates

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Chromate, molybdate, or tungstate substituted the place of the
sulfate group. These minerals are usually brightly colored,
brittle and dense.

Chromates,
molybdate,
tungstates

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One or more metal is chemically combined with the
phosphates, arsenates, vanadates group.

Phosphates,
arsenates,
vanadates

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This is the largest mineral group. Minerals under this group
have different amounts of silicon and oxygen

Silicates

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Analysis of the Composition and
Crystal Structure of Minerals

Wet chemical analysis
Spectroscopic techniques

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involves dissolving a mineral in an acid and analyzing the solution.

Wet chemical analysis

involve quantitative analysis of mineral components depending on the light absorbance of the compounds.

Spectroscopic techniques

most common rock-forming minerals

quartz feldspar mica, pyroxene amphibole olivine.

most common rock-forming minerals

quartz feldspar mica, pyroxene amphibole olivine.

Self-colored minerals are called Their color is a diagnostic property. This means that the color of a mineral is constant and it depends on the elements that make up their chemical structure. Examples are malachite (always green), rhodochrosite (always red) and sulfur (always yellow).

idiochromatic minerals

color is not a reliable diagnostic property since small impurities may dramatically alter their color. For example, quartz may occur in different varieties. This includes colorless, milky, smoky, citrine, amethyst, and rose as shown below are often weakly-colored or colorless in their pure state, which allows impurities to pervade them with color

allochromatic minerals

are false-colored minerals. Their colors are due to light diffraction. In this instance, color may be variable but is an exclusive properties of the mineral.

pseudochromatic minerals

classifications of mineral color

idiochromatic allochromatic pseudochromatic

Minerals appear the same as a pearl or the abalone shell’s interior.

pearly (luster)

It shows similar properties with silk which has fine parallel threads.

silky (luster)

A mineral has a plain-looking sheen.

dull (luster)

Its characteristics are the same with a resin or chewing gum.

resinous (luster)

Minerals are opaque and looks like Earth or dirt.

earthy (luster)

Minerals are very shiny and brilliant.

adamantine (luster)

occurs if it has the same sheen as a glass.

vitreous or glassy (luster)

A mineral has the same appearance as a polished metal.

metallic (luster)

types of luster

pearly silky dull resionous earth adamantine vitreous or glassy metallic

Needle-like. Its size is wider than fibrous but thinner than prismatic.

acicular

Its shape is rectangular, but the sides are not necessarily flat.

blocky

Tablet-like. It has flat squares.

tabular

Furry-like. Its sides are thinner than acicular.

fibrous

Its shape is like a knife.

bladed

Plant-like.

dendritic

Pencil-like. Its sides are thicker than acicular.

prismatic

types of crystal habit

acicular blocky tabular fibrous bladed dendritic prismatic

1 cleavage planes on top of the other

basal

2 cleavage cleavage at right planes

prismatic

2 cleavage cleavage not at right angles

non-prismatic

3 cleavage cleavage at right angles

cubic

3 cleavage cleavage not at right angles

rhombohedral

4 cleavage formed 8 faces

octahedral

4 cleavage formed 12 faces

sphalerite

types of cleavage

basal prismatic non prismatic cubic rhombohedral octahedral sphalerite

Fracture looks like a semi-circular shell.

conchoidal

Fracture appears as jagged points. It has sharp and rough surface.

jagged

Splintery-fibrous-like fracture

splintery

Rough and irregular fracture. Common in most minerals.

uneven

Types of fracture

conchoidal jagged splintery uneven

relative Mohs scale of hardness

talcm gypsum calcite fluorite apatite feldspar quartz topaz corundum diamond

The Geologist Can Find An Ordinary Quartz Tourists Call Diamond

involves dissolving a mineral in an acid and analyzing the solution. An acid used is usually hydrochloric acid (5-10%). If a bubble is evident after putting drops of the acid, it indicates that carbonate minerals such as calcite and dolomite is present.

wet chemical analysis

uses a controlled flame to separate the components of a sample and monochromator linked to a detector to search for wavelengths of light that are absorbed by the sample

Atomic absorption spectroscopy (AAS)

uses argon gas to move the sample vapor into a chamber under high vacuum where both the sample and the gas are heated for the elements to give off a characteristic wavelength of light. This technique is able to trace and identify almost all the minerals present in the sample.

Inductively coupled plasma (ICP) spectroscopy

uses high voltage electrons toward a metal target to produce a specific wavelength X-ray beam that hits the sample. Comparing the sample intensities to that of the standard can be used to calculate the concentration of elements present in the mineral. This technique will give an analyst a real-time rock analysis. This is more convenient and efficient than the older technique which takes weeks before analysis is presented.

X-ray fluorescence (XRF) spectroscopy

is a technique that only applies to pure amorphous or crystalline substances and is used to study the structure of the crystals. This process is done by firing an X-ray beam at a finely-ground sample at different angles. Then reflected or diffracted rays can be used to compute for the dimensions of the unit cell. This technique is used to obtain information from unknown crystalline substances particularly most minerals.

X-ray diffraction spectroscopy (XRD)

has a chemical composition of SiO 2 . It is a glass-like hard substance with white streaks. It has Mohs hardness of 7 which makes the _ grains resist scratching of nail or a pocket knife. Pure _ is also known as “rock crystal” that is colorless and transparent. Trace amounts of impurities cause colored varieties of _. _ can occur as amethyst (purple-violet), citrine (yellow), smoky or cairngorm (brown), morion (black), rose (pink), sapphire _ (blue), and milky (semi-translucent white). The grains of _, in general, are irregular in shape and exhibits conchoidal fracture.

quartz

has a chemical composition of XAlSi 3O 8 , where X is potassium (K), calcium (Ca), or sodium (Na). It is quite hard with a Mohs hardness of 6. It is a light-colored mineral, usually white, but can also exist in lighter shades of red or green. It has a glassy luster. In rocks, _ forms rectangular crystals that break along flat faces.

feldspar

[KAl 3AlSi 3O 10 )(OH) 2 ] occurs as a white, shiny and silvery mineral. It has a pearly to vitreous luster, white streak and often sheds into tiny flakes when scratched.

Muscovite mica

[K 2 (Mg,Fe) 3AlSi 3O 10 (OH,O,F) 2 ] is black, dark green, or dark brown, shiny, and often occurs in small-hexagonal crystals. It has a vitreous luster, flaky habit and white to gray streak. _ sheets are elastic when bent.

Biotite mica

minerals have a general composition of XY(Al,Si) 2O 6 where X is calcium (Ca) or magnesium (Mg) and Y is either magnesium (Mg), iron (Fe), or aluminum (Al). It occurs as short, stubby and black to dark-green crystals (although other colors may occur). It has a glassy luster with streaks of white, light green, or light brown. It has good cleavage in two directions (both at almost 90°) and cleavage surfaces are often hard to see in a regular rock sample. Augite is the most common mineral of this group.

Pyroxene

has a general formula of W 0-1X 2Y 5Z 8O 22 (OH) 2 and has a dark color with a Mohs hardness ranging from 5 to 6. It is opaque and has a glassy luster. It occurs as long and slender crystals. It has good cleavage in two directions (approximately 60°and 120°) and therefore has a stair-step appearance under a hand lens. Hornblende is the most common amphibole.

Amphibole

is a silicate mineral with a general chemical composition of (Mg,Fe) 2SiO 4 , but calcium, manganese, and nickel can be substituted for magnesium and iron. It occurs as small, light green, glassy crystals. It is commonly used in the gemstone industry as peridot. It is a glassy looking and transparent substance that is almost as hard as quartz. Its sugary or sacharroidal texture and olive-green color make it distinctive from other rock-forming minerals.

Olivine