Earth Materials Exam One

Who was James Dana and Why do we care?

James Dana defined what a mineral was with a mineral classification scheme

What is the IMA

International Mineralogical Association

Mineral names and nomenclature with specific criteria that must apply for the substance to be considered a mineral

What is the definition of a mineral?

A naturally occurring, homogenous, well-defined composition, inorganic crystalline substance

What is mineral variety?

Minerals of the same chemical composition with variances in crystal shape and color

What is the difference between ruby, sapphire, and corundum?

They are different forms of the same mineral (corundum = Al2O3)

What is a biomineral? and name three most common ones

Crystalline materials produced by living organisms; teeth (apatite), clam shells (calcite), diatoms (SiO2)

Is amber a mineral?

No because it is made from tree sap which is not crystalline

Is ruby a mineral?

Yes

Is coal a mineral?

No, it is a rock

Is graphite a mineral?

Yes

Is volcanic glass a mineral?

No because it is non-crystalline

Differentiate rocks and minerals

Elements combine to form naturally occurring crystalline solid minerals, minerals combine to form rocks

What are the two major factors used for the classification of minerals?

structure and composition

What are some properties of minerals that are controlled by their structure?

crystal form, crystal habit, cleavage, streak, luster, tenacity, density, color, conductivity

Why do we care about the chemistry of a mineral?

to characterize minerals, to determine how and where a mineral forms and to learn about Earth’s conditions, to determine the economic significance of a mineral,

What aspect of the mineral chemistry is the basis for this classification?

The dominant anion or anionic group

Give examples of 4 of these major mineral classes

Oxides (O), phosphates (PO4), halides (Cl, F, Br, I), carbonates (CO3), silicates (Si and O), sulfates (SO4)

Si⁴⁺ atoms are surrounded by how many oxygens in most silicate minerals?

What is the shape of this Si-O unit?

What is the charge of this unit?

4 b/c (SiO4)^-4

tetrahedron

4-

What color is olivine?

What is the name of the gem variety of olivine?

Green

Peridote

How many of each atom are in the following mineral Olivine (Mg,Fe)2 SiO4

2 atoms of Mg or Fe or some combination of that Fe+Mg=2, 1 atoms of Si, 4 oxygen

How many of each atom are in the following mineral Marialite Na4 (AlSi3O8)3Cl

4Na, 3Al, 9Si, 24O, 1Cl

Why study minerals?

Basic building blocks of the Earth, most of all solid Earth processes relate in some way to physical or chemical properties of minerals, minerals are the fundamental key to understanding the evolution of the solid Earth, economic significance

How many of each atom are in the garnet with this formula: Garnet (Mg, Fe, Ca)3Al2Si3O12

2Al, 3Si, 12O, and Mg+Fe+Ca=3 in any combination

What is mineral cleavage?

and give an example

Mineral cleavage is a plane along which a mineral breaks and is controlled by the structure. Planes with the weakest bonds will have the most prominent cleavage.

Biotite has a “basal cleavage” b/c of the weak bonds btwn the layers

List these from softest to hardest with the Mohs hardness scale: quartz, fingernail, apatite (teeth), pocket knife

soft to hard: fingernail (2.5), apatite (5), pocket knife (5.5), quartz (7)

What mineral will fizz if you put dilute HCl (hydrochloric acid) on it?

calcite (CaCO3)

What mineral habit is displayed? and name the mineral

blocky Halite - NaCl

What mineral habit is displayed here? and name the mineral

Botryoidal (bulbous, rounded forms) Hematite - Fe2O3

What type of luster is displayed here? and name the mineral

vitreous (glassy) Calcite

What type of luster is displayed here? and name the mineral

greasy Opal

What is this type of property called? and name the mineral

“Play of colors,” and “Shiller” effect from light scattering off, Labradorite

What type of cleavage is this? and name the mineral

octahedron, fluorite

What mineral habit is displayed here? name the mineral

fibrous (whisker-like), amphibole

What mineral habit is displayed here?

reticulated (forms a network)

what mineral habit is displayed here?

platy

what mineral habit is displayed here?

stellate (arranged in a radiating pattern like that of a star)

What mineral habit is displayed here?

radiating pyrite

what mineral habit is displayed here? and name the mineral

prismatic, gypsum

what mineral habit is displayed here?

needle-like

What are the three types of luster and what are their meanings?

metallic: shiny appearance like polished metal, submetallic: not quite so shiny, nonmetallic: dull

What type of luster is displayed here?

resinous

what type of luster is displayed here? and name the mineral

silky, gypsum

What is the term for crystals that sparkle and appear brilliant?

adamantine minerals

What type of luster is displayed here?

pearly

what type of luster is displayed here?

dull

What is the term for “ability to transmit light”

diaphaneity

Name the differences between transparent, translucent, and opaque

transparent is clear, translucent transmits light but not clearly, opaque does not transmit light

Name some reasons for color in minerals

metal ions, intervalence charge transfer, ionizing radiation, physical effects, band gaps

what is the streak of a mineral

the color the mineral has as a fine powder

what is luminescence

emit light when activated by energy other than visible light

What play of color is this mineral displaying?

Tiger’s Eye

What are these plays of color displaying and name the mineral

Moonstone - K feldspar, Chatoyancy (band of light), Asterism

What is cleavage of a mineral?

Breaking along smooth planar surfaces oriented along planes of weakness in the lattice

What is fracture of a mineral?

breaking in orientations unrelated to the lattice structure

What type of cleavage does biotite (mica) have?

Basal cleavage

What type of cleavage does Pyroxene have?

90 degrees btwn planes

What type of cleavage does Amphibole have?

60 degrees and 120 degrees btwn planes

What is hardness?

a mineral’s resistance to abrasion or scratching

Minerals with this element typically have magnetic properties

Fe (iron)

What are the three categories of magnetism and their meanings?

ferromagnetic are strongly attracted to magnets, diamagnetic are weakly opposed (repelled) by strong magnets, paramagnetic is weakly attracted to strong magnets

What native element has a high conductivity?

copper

List the names of the 7 crystal classes

Give the relative axial lengths for each crystal class

Give the relative axial angles for each crystal class

Cubic/isometric, a=b=c, A=B=C=90

Tetragonal, a=bcc, A=B=C=90

Orthorhombic, a≠b≠c, A=B=C=90

Rhombohedral, a=b=c, A=B=C≠90

Monoclinic, a≠b≠c, A=C=90, B≠90

Triclinic, a≠b≠c, A≠B≠C≠90

Hexagonal, a=b≠c, A=B=90, C=120

What are the 3 primary symmetry operations used to describe mineral symmetry?

rotation, reflection (mirror), rotoinversion

What fold rotation axis is represented by each of these symbols? oval, triangle, square, hexagon

2, 3, 4, 6

What are the Miller Indices of this plane?

(111)

What symmetry operations are indicated by these stereonets?

2-fold rotation axis with no mirror, 4-fold rotation axis with no mirror,

What is the fold axis of this crystal? What is the orientation of the rotation axis? What does the steronet look like?

2-fold axis, oriented vertically, oval in the middle with 2 dots inside a dashed circle

How many mirror planes are in this crystal? Where is/are the mirror plane(s) oriented? What does the steronet look like?

one mirror, oriented vertically splitting the 2 bevels

A cube has the highest symmetry of (picture). what does each of these mean

4/m = 4-fold rotation axis with a mirror plane perpendicular

3-bar = 3-fold rotoinversion axis

2/m = 2-fold rotation axis with a mirror plane perpendicular

What are the 5 unit cell types?

primitive, body centered, face centered, side centered, rhombohedral

What is the difference between a dipyramid and an octahedron?

Octahedron is cubic/isometric with a=b=c with all angles = 90 degrees while tetragonal dipyramid is tetragonal with a=b≠c with all angles = 90 degrees

Name this twin and the mineral

penetration twin, staurolite

Name the twin and the mineral

Penetration twin, pyrite

Name the twin and the mineral

Contact twin, gypsum

Name the twin and the mineral

polysynthetic twin, albite

What is the crystal system represented by the form?

Isometric

What is the crystal system represented by the form?

Hexagonal and Trigonal

What is the crystal system represented by the form?

Tetragonal

What is the crystal system represented by the form?

Orthorhombic

What is the crystal system represented by the form?

Monoclinic

What is the crystal system represented by the form?

Triclinic

What type of twin is shown?

cyclic

What twin is displayed? of what mineral?

Japan Law, quartz