Immediately to the west of Nongkai, through Loei province close to the Pasak river, and south to Lopburi there is a mineral zone shown on the modern map as having deposits of copper, iron, gold, and lead. Farther north and west, from Chiengrai to Tak there is another band of the same minerals, plus a smaller area near Maehongsorn in which a tin deposit is noted, and gold. Outside of the well-know tin ore in the peninsula, most of these metals do not now exist in sufficient quantity or in the from for modern commercial value, but their existence argues that there may have once been more easily extractable deposits in the vicinity.