《明史·列传·卷一百九十三》
十六年，宦官使者上五台山祭祀，回来后说紫荆山外的广昌、灵丘有矿砂，可以炼银。
十六年，中使祠五台山，还言紫荆关外广昌、灵丘有矿砂，可作银冶。
In the sixteenth year, an eunuch sent as an emissary to sacrifice at Wutai Mountain returned and reported that there was mineral ore in Guchang and Lingqiu outside of Zijing Mountain that could be refined into silver.