At background levels, frequency distributions truncated (censored) in most natural media
Tourmaline (typical formula NaFe++3Al6[BO3] 3Si6O18[OH]4) is an important accessory mineral in many types of gold deposit. However, this mineral is resistant to the strong-acid digestion routinely used in geochemical laboratories and dispersion patterns of B thus analyzed may be difficult to interpret.
2. As an Aid to Geological MappingElevated B values may serve to "fingerprint" felsic intrusive rocks of distinctive composition and origin