Table 1. Units and symbols

Length (l)

m = meter(s)

cm = centimeter(s) (1 cm = 10^-2 m)

mm = millmeter(s) (1 mm = 10^-3 m)

μm = micrometer(s) (1 μm =10^-6 m) NOT micron or μ

nm = nanometer(s) (1 nm = 10^-9 m)

Å = angstrom(s) (1 Å = 10^-10 m)

pm = picometer(s) (1 pm = 10^-12 m)

in. = inch(es) (not recommended)

Volume (V)

L = liter(s)

mL = milliliter(s); cm³ = cubic centimeter(s)

ų = cubic angstrom(s)

Mass (m)

g = gram(s); kg = kilogram(s); mg = milligram(s); μg = microgram(s)

Density (D or ρ)

g/cm³ = gram(s) per cubic centimeter

Concentration (indicate with square brackets [ ] around chemical symbol, e.g., [Cl^1-])

% = percent; ‰ = per mill

wt% = weight percent; mol% = mole percent; vol% = volume percent

M = molar concentration (1 M = 1 mol/L)

m = molal concentration (1 m = 1 mol/kg)

ppm = parts per million; ppb = parts per billion

Time (t)

s = second(s); min = minute(s); h = hour(s); d = day(s); yr = year(s)

Ma = million years; Ga = billion years (ago or date)

m.y. = million years; b.y. = billion years (duration)

Pressure (P)

Pa = pascal(s)

kPa = kilopascal(s); MPa = megapascal(s)

GPa = gigapascal(s)

bar or bars (no abbreviation)

kbar = kilobar(s)

atm = atmosphere(s) (not recommended)

Temperature (T)

K = Kelvin(s)

°C = degrees Celsius

Frequency (f or η)

Hz = hertz; kHz = kilohertz; MHz = megahertz

Energy

J = joule(s); kJ = kilojoule(s) (preferred)

cal = calorie(s); kcal = kilocalorie(s)

Miller indices--note that letter symbols are italicized but numberic values are not, e.g., [hkl] but [100]

hkl = diffraction symbol

(hkl) = face symbol

{hkl} = form symbol

[hkl] = edge or zone symbol

Unit-cell measurements

a, b, c = edge lengths; α, β, γ = angles

a, b, c = vectors--note boldface

Optical measurements:

dispersion (r, v),
optic axial angle (2V, 2V_x, 2V_z);
principal vibration directions (E, O; X, Y, Z);
refractive indices (n; nε, nω, nα, nβ, nγ where the n's are italic and the greek characters are subscripts)

Other abbreviations (roman type); cf. = compare; e.g. = for example; et al. = and others; etc. = and other things; i.e. = that is; p. = page(s); vs. = versus.