347K FIRST Hour EXAM
October 3, 1994Answer the following questions as directed. For multiple choice
questions choose the single best answer. Multiple choice are worth 3 pts, T/F are
worth 1 pt. each. Answers are highlighted in red.
1) What is the difference between hardness and toughness (tenacity)? Give
an example of a mineral that is hard but not particularly tough, or tough but not
particularly hard.(4 pts.)
2) Why aren't all minerals gems and all gems minerals? b) Give an example
of a mineral that is not a gem and a gem that is not a mineral. (4 pts.)
3) If gemstone A is the same size, shape (cut) and weight as gemstone B then we may
conclude that
a) gemstone A and B are the same materials.
b) gemstone A and B have the same specific gravity.
c) gemstone A is an imitation of gemstone B.
d) they are both of equivalent value.
e) a and b.
4) If cubic zirconia has a specific gravity that is higher than that of diamond, then identically
cut and faceted diamond and cubic zirconia gemstones will
a) weigh the same amount because they are cut the same.
b) weigh different amounts; the diamond will be heavier.
c) weigh different amounts; the cubic zirconia will be heavier.
d) weigh different amounts, but which is heavier will depend on how big they are.
e) weigh the same amount because they have very similar physical properties.
5) Crystalline materials differ from amorphous materials by
a) containing different chemical elements.
b) having periodic spacing of atoms.
c) being natural rather than man-made.
d) a and b.
e) all of the above.
6) Step-cut gemstones can be distinguished from brilliant-cut gemstones by
a) the shapes of the facets.
b) the size of the table.
c) whether the crown is domed or flat.
d) the strength of the play-of-color.
e) the number of facets; brilliant cuts have more facets than step cuts.
7) Concoidal fracture is
a) common in minerals that contain 2 cleavages.
b) common in minerals that contain 1 cleavage.
c) common in minerals that do not have a cleavage.
d) a fracture pattern that looks like splintered wood.
e) restricted to minerals that have high specific gravities.
8) Cleavage and parting are two physical properties that affect a gem or mineral's
a) toughness
b) hardness
c) durability
d) a and c
e) all of the above.
9) A Mohs hardness of 7 is often considered the minimum for jewelry gemstones because
softer gems
a) break to easily.
b) can't be polished.
c) are too easily scratched.
d) a and c
e) all of the above.
10) Which of the following is correctly arranged by hardness?
a) Corundum, topaz, orthoclase, quartz
b) Fluorite, orthoclase, quartz, topaz.
c) Quartz, corundum, topaz, diamond.
d) Diamond, corundum, quartz, topaz.
e) Talc, gypsum, fluorite, calcite.
11) A gemstone that floats on top of a heavy liquid has a specific gravity that is
a) the same as the liquid.
b) greater than the liquid.
c) less than the liquid.
d) greater than or less than the liquid, depending on size of the gemstone.
e) none of the above
12) A mineral's luster is a physical property that depends on the
a) diffraction of light from the mineral's surface.
b) the reflection of light from the minerals
surface.
c) the absorption of different wavelengths of light at the minerals surface.
d) the presence or absence of a chromophore.
e) the emission of light after some light is absorbed.
13) Asterism is caused by
a) the presence of more than one chromophore.
b) randomly arranged, reflective mineral inclusions.
c) color centers.
d) diffraction in more than one direction.
e) none of the above
14) Tiger's eye or gems that display a cat's eye exhibit a phenomenon called
a) asterism
b) chatoyance
c) play-of-color
d) aventurescence
e) none of the above
15) To see the green color in an emerald, the Cr present must absorb the
a) green part of the visible spectrum.
b) yellow part of the visible spectrum.
c) red part of the visible spectrum.
d) blue part of the visible spectrum.
e) part of the infrared spectrum.
16) Gem labradorite feldspar and opal owe their unique color displays to
a) aventurescence.
b) color centers.
c) fluorescence.
d) transition metal chromophores.
e) diffraction
17) Play-of-color is a term used to describe
a) different colors caused by many different chromophores.
b) the difference between hue and tone.
c) flashes of color in opal.
d) aventurescence in sunstone.
e) a particularly vibrant Broadway show.
18) Aventurescence is a phenomenon caused by
a) reflective mineral inclusions.
b) fluorescence in moonstone.
c) diffraction.
d) color centers.
19) Fluorescence of a gem in ultraviolet light is a result of
a) the emission of ultraviolet light.
b) dispersion.
c) diffraction.
d) the absorption of visible light.
e) the absorption of ultraviolet light and the emission of visible
light.
20) Color in allochromatic minerals and gems is
a) a diagnostic property that can aid in mineral or gem identification.
b) caused by chromophores that are present in great abundance.
c) not a diagnostic property for identification purposes.
d) caused by reflection from randomly arranged mineral inclusion.
e) none of the above.
21) Color centers are the source of color in minerals that
a) contain transition elements.
b) are ideochromatic.
c) are capable of diffracting light.
d) contain crystal lattice defects.
e) are fluorescent.
22) Absorption of light by chromophores to produce color occurs
a) within the nucleus of the chemical element that is the chromophore.
b) by moving a proton from one type of orbital to another.
c) when atoms can move from one site within a crystal to another, absorbing energy.
d) by the movement of electrons.
e) by diffraction.
23) Transition elements are uniquely suited to act as chromophores because they
a) contain electrons in partially filled d-orbitals.
b) are electrically neutral.
c) are the most common elements in nature.
d) are highly mobile in crystals.
e) all of the above.
24) A gem or mineral that is red absorbs
a) red light.
b) mostly red light.
c) mostly green light.
d) more of the visible spectrum than a gem or mineral that is violet.
e) less of the visible spectrum than a colorless gem.
25) Gems and minerals whose color can be altered by high energy forms of radiation are
colored by
a) color centers
b) diffraction
c) transition elements
d) play-of-color
e) none of the above
26) In crystallography, a form is defined as
a) the habit of the mineral.
b) a group of identical crystal faces.
c) a group of crystal faces with adjoining edges.
d) a specific type of symmetry element.
e) an incomplete crystal.
27) The internal arrangement of atoms in crystalline materials is reflected in the
external shapes of crystals by
a) the angles between crystal faces.
b) the symmetry of crystal faces.
c) the shape of the smallest, imaginary "building block" needed to construct the
crystal.
d) all of the above.
28) The symmetry of crystal faces with respect to a line, plane and/or point can be
used to classify crystals into
a) crystal habits.
b) closed or open crystal forms.
c) crystal interfacial angles.
d) crystal systems.
e) none of the above.
29) The hexagonal crystal system differs from all others in being composed of a unit
cell that
a) has 4 imaginary axes.
b) has a long c-axis.
c) is smaller than all the others.
d) has sides that are not at right angles.
e) has 6 faces.
30) The isometric (cubic) crystal system is characterized by having
a) 3 crystallographic axes of equal length.
b) 4 crystallographic axes of unequal length.
c) no crystallographic axes perpendicular.
d) no crystallographic axes of equal length.
e) 3 crystallographic axes of unequal length.
31) Minerals that form crystals that fall within the tetragonal crystal system can
a) also form crystals of the isometric system.
b) grow crystals of different shapes, but all the crystals will still have the symmetry of
the tetragonal system.
c) also form crystal that have symmetries appropriate to any of the crystal systems.
d) show nearly an infinite variety of symmetries.
e) have only a center of symmetry.
32) Most common gem minerals are members of the
a) isometric, tetragonal and hexagonal crystal systems
b) monoclinic and triclinic systems
c) orthorhombic and isometric systems
d) isometric system
e) orthorhombic system
33) Prism and pinacoids are types of
a) open forms
b) crystalline solids
c) symmetry operators
d) crystallographic axes
e) closed forms
34) Hue is the term used to describe the
a) amount of brown or gray present in a color
b) vibrancy of a color
c) color present (red, blue, green, etc.)
d) darkness or lightness of the color
e) none of the above.
Answer the following questions True or False.
35) __F__ White is seen when all wavelengths of the visible spectrum are absorbed.
36) __T__ Opal with well-organized spherical molecules of the proper size and spacing
will show play-of-color.
37) __F__ The crown facets on a gemstone are below the girdle.
38) __F__ Ideochromatic gems, in their purest form, are colorless.
39) __F__ There are 5 grams in one carat.
40) __T__ Allochromatic materials, in their purest forms, are colorless.
41) __T__ Chromium can produce different colors in different minerals.
42) __F__ All crystalline materials belong to one of the 5 crystal systems.
43) __T__ A rhombohedron is an example of a closed form.
44) __F__ S-, p-, and d-orbitals are location where light is absorbed in elements that
are chromophores.
45) __T__ Brilliant-cut gemstones can be distinguished from step-cut gemstones by the
shapes of the facets.
46) __F__ An adamantine luster is less lustrous than a vitreous luster. |
