Page 10 - A Practical Introduction to Optical Mineralogy

SYMBOLS AND ABBREVIATIONS
List of symbols and abbreviations principal reflectance corresponding to ordinary ray vibration direction of a
I ''
uniaxial mineral
used in the text principal reflectance corresponding to extraordinary ray vibration direction of a
uniaxial mineral
bireflectance (Rmax - Rm;n) referring to individual section or maximum for
mineral
Crystallographic properties of minerals
abc orXY Z crystallographic axes Quantitative colour
hkl Miller's indices, which refer to crystallographic orientation
I I visual brightness
( I II) a single plane or face ,, dominant wavelength
f:: ~j a form ; all planes with same geometric relationship to axes 1', ,, saturation
zone axis; planes parallel to axis belong to zone
chromaticity co-ordinates
/3 angle between a and c in the monoclinic system
a,f3,y angles between band c, a and c, and a and bin the triclinic system
Mineral properties
Light liN Vickers hardness number
II hardness on Moh's scale
ft. wavelength
/I density
A amplitude ,, specific gravity
PPL plane or linearly polarised light
General
Microscopy
I' pressure
N, S, E,W north (up), south (down), east (right), west (left) in image or in relation to
I temperature
crosswires
HI X-ray diffraction
NA numerical aperture
C II . rare earth elements
X POLS, XP, CP crossed polars (analyser inserted) nanometre
IIIII
micro metre or micron
I'"'
Optical properties IIIII I millimetre
nor RI refractive index of mineral Ill centimetre
N refractive index of immersion medium tl distance or length
RI of ordinary ray angstroms
RI of extraordinary ray cleavage
n. minor RI " kilo bar
np intermediate greater than
n, major RI less than
greater than or equal to
0 ordinary ray vibration direction of uniaxial mineral
e extraordinary ray vibration direction of uniaxial mineral less than or equal to
a,{3, y principal vibration directions of general optical indicatrix approximately
8 maximum birefringence (n. - n 0 or n , - n. ) approximately equal to
2V optic axial angle perpendicular to
2V. optic axial angle bisected by a parallel to
2V, optic axial angle bisected by 'Y I four or greater
Bx. acute bisectrix (an acute optic axial angle) II three dimensional
obtuse bisectrix (an obtuse optic axial angle) / II I I• • ~ S association of elements in ternary chemical system
BX 0
, ,, 1.. s association of elements
OAP optic axial plane
y·cl angle between 'Y (slow component) and cleavage
a ·cl angle between a (fast component) and cleavage
k absorption coefficient
R reflectance (usually expressed as a percentage, R %)
R mtn minimum reflectance of a polished section of a bireflecting mineral grain
Rmax maximum reflectance of a polished section of a bireflecting mineral grain
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