Mineralogy 1 Flashcards
arrange the oxides by weight:
Al2O3
CaO
TiO2
H2O
SiO2
MgO
K2O
Na2O
Fe2O3
FeO
Remaining oxides
SiO2
Al2O3
CaO
FeO
Na2O
MgO
K2O
Fe2O3
H2O
TiO2
Remaining oxides
olivine, garnet, zircon, kyanite are example of what tetrahedron configuration
Isolated (nesosilicates)
epidote, zoisite are example of what tetrahedron configuration
Pairs (sorosilicates)
Tourmaline is an example of what tetrahedron configuration
Rings (cyclosilicates)
pyroxenes, wollastonite are example of what tetrahedron configuration
single chains (inosilicates)
amphiboles are example of what tetrahedron configuration
double chains (inosilicates)
Micas, clay minerals, serpentine, chlorite are example of what tetrahedron configuration
sheets (phyllosilicates)
felds, quartz, zeolite are example of what tetrahedron configuration
framework (tectosilicates)
intergrowth of sodic and potassic felds resulting from subsolidus exosolution (unmixing of two minerals
has blebs or irregular lamellae of sodic feldspar within potassic alkali feldspar
Perthite
intergrowth of branching rods of quartz set in a single crystal of plag
derived from the ancient greek work “myrmekia” (wart)
Myrmekite
appearance of runic writing
suggested to originate by simultaneous crystallisation
Graphic Texture
solid solution phase umixes into two separate phases in the solid state
Exosolution lamellae in pyroxene
the same direction in all directions
(garnet, spinel)
equant
equant with a nearly square cross sections
(halite, galena)
blocky
needlelike
(actinolite, sillimanite)
acicular
plates or thick sheet
(gypsum, graphite)
tablular or platy
hairlike or threadlike (serpentine, millerite)
capillary or filiform
elongated and flatened in one direction (kyanite, wollastonite)
bladed
elongated with faces parallel to a common direction (apatite, beryl)
prismatic or columnar
easily split into sheets (muscovite, biotite)
foliated or micaceous
solid mass with no distinguishing features
massive
composed of many individual grains
granular
crystals emanating from a common point
radiating or divergent
composed of fibers
fibrous
stalactite shaped
stalactitic
plates or slaps growing together
lamellar or tabular
contains aggregate of crystals giving a starlike appearance (pyrophyllite)
stellated
feathery appearance
plumose
like a branching tree or plant
dendritic or arborescent
net-like, lattice pattern
reticulated
spherical/hemispherical shapes made of radiating crystals
colloform or globular
similar to a bunch of grapes (hematite)
botryoidal
kidney-shaped
reniform
breast-like
mamillary
surfaces covered with fine crystals
drusy
small or small spheres
elliptic or pisolitic
mineral habit characterized by small, strong and flexible fibers.
asbestiform
commercial name for any marketable asbestiform mineral
asbestos
“white asbestos” is composed of what mineral?
serpentine mineral group
accounts for 95% commercial asbestos market
chrysotile
“blue asbestos”
variety of riebeckite
crocidolite
“brown asbestos”
variety of grunerite
amosite
when a mineral changes color as it is rotated to the polarizer in PPL
pleochroism
characterizes the relationship between the speed of light in a vacuum and the speed of light in that mineral
refractive index
refractive index of High mineral relief
> 0.12
refractive index of intermediate relief
0.04 - 0.12
refractive index of low relief
<0.04
relative refractive indices of two materials (minerals, glass, or epoxy) adjacent to each other in a thin section can be determined by using
Becke lines
if Becke line moves into the mineral grain the mineral has a _____ index of refraction and _____ relief
higher, higher
if Becke line move out of the grain, the mineral has a ____ index of refraction and _____ relief
lower, lower
ideal crystal form or the shape of a mineral takes when left to grow without barriers or interface with other nearby mineral grains
Mineral form
minerals show perfect or nearly perfect crystal faces
euhedral
minerals are rounded but still show general characteristic shape of that mineral
subhedral
crystals are completely irregular in shape and do not resemble the characteristic form for that mineral
anhedral
tendency of minerals to break along atomic planes of weakness within the crystal structure
cleavage
irregular cracks within a mineral
fractures
under XPL, the mineral will go extinct (dark) when the cleavage direction is PARALLEL to the N-S and E-W directions as the stage is rotated. what extinction is this?
parallel extinction
color of mineral under XPL is called
interference color
mineral separates into two minerals, producing a striped effect
exosolution lamellae
rocks in which clay content is predominant
soft in nature and with the presence of water, they crumble easily
if dry, crushed easily because of brittleness
ex. shale, slate, laterite
argillaceous rocks
rocks in w/c calcium carbonate is the major ingredient
generally hard but their durability is dependent on surrounding constituents
ex. marble, limestone, dolomite
calcareous rocks
rocks contain silica in predominant amount
presence of a large of free silica makes them harder and durable. strong resistance to weather
ex. granite, chert, quartzite
siliceous rocks
twinning that has a planar composition surface separating two individual crystals.
ex. orthoclase twinned on the Braveno law, with {021} as the twin plane
contact twins
twinning that has a planar composition surface separating two individual crystals.
ex. crystal of orthoclase twinned on the Braveno law, with {021} as the twin plane
contact twins
twinning that have an irregular composition surface separting two individual crystals
defined by a twin center or twin axis
ex. crystal of orthoclase twinned on the Carlsbad Law with [001] as the twin axis
penetration twins
composition surfaces are parallel to one another
ex. plagioclase, albite twin law with {010} as the twin plane
polysynthetic twin
composition surfaces are not parallel to one another
ex. chrysoberyl along {031} plane
cyclical twins
feldspar minerals plagioclase and microcline are the most common that show twinning in this system
triclinic system
this system is most commonly occur on the plane {100} and {001}
orthoclase and sanidine most commonly twinned
both contact and penetration twins occur
Maneback law {001}, contact twin
Carlsbad Law [001], penetration twin
Braveno Law {021}, contact twin
Swallow Tail Twins {100}, gypsum
monoclinic system
commonly twin on planes parallel to a prism face
{110} cyclical twins
Staurolite Law
orthorhombic crystal (orthorhombic system)
twinning in this system usually occurs on {011} forming cyclical contact twins
ex. rutile and cassiterite
tetragonal system
three types of twins common in isometric system
Spinel Law {111}, spinel
[111]
Iron cross [001], pyrite
