1. A method of determining fracture geometry of a subterranean formation from radiation emitted from a fracture in said formation, comprising: a) measuring gamma-radiation emitted from the fracture; b) subtracting background radiation from said measured gamma-radiation to obtain a peak-energy measurement; c) comparing said peak-energy measurement with a gamma-ray transport/spectrometer response model; and d) determining formation fracture geometry of said fracture in accordance with values associated with said response model.