1. A method for estimating an aspect of a formation using a nuclear spectroscopy tool, comprising: placing a nuclear spectroscopy tool including a neutron source and a gamma ray detector into a borehole; performing a plurality of environmental measurements; emitting neutrons from the nuclear spectroscopy tool such that some of the neutrons can generate gamma rays from a formation adjacent the nuclear spectroscopy tool and some of the neutrons can generate gamma rays from elements within the nuclear spectroscopy tool; detecting an energy spectrum of gamma rays induced by the emitted neutrons, the energy spectrum including a tool background comprising the gamma rays from elements within the nuclear spectroscopy tool having a plurality of measured spectral components including an iron spectral component; estimating a background ratio between the iron spectral component of the tool background and at least one other spectral component of the tool background in accordance with the plurality of environmental measurements; analyzing the detected gamma ray spectrum using a combination of standard spectra and subtracting the iron spectral component of the tool background in accordance with the background ratio; and estimating an aspect of the formation based on the analyzed spectrum.