Hsieh Ju-chuan, whose child married Yen Yun-nien's, once wrote that Yen was more obsessed by coal than by gold, assigning his younger brother Yen Kuo-nien to find coal fields.
顏雲年的兒女親家謝汝銓曾為文指出，顏雲年不僅致力於金，更留心於煤，並委交弟弟顏國年搜尋炭脈，大小礦區一共得到五十三處。