Apparatus and methods for consolidating granular silicon and determining trace elements content of the consolidated silicon are disclosed. Silicon granules are placed in a vessel, and a silicon slug of known purity is embedded at least partially in the granules. The slug is preheated to a temperature sufficient to couple with an induction heater. As the silicon slug melts, silicon granules adjacent the molten silicon also melt. The vessel passes through an induction coil to successively inductively heat and melt regions of the silicon granules from the leading end to the trailing end with each region solidifying as the molten silicon exits the induction coil to provide a multicrystalline silicon ingot. The multicrystalline silicon ingot is sliced into wafers, which are analyzed by low-temperature Fourier transform infrared spectroscopy to determine levels of trace elements in the ingot.