This paper presents some statistical results of calculating the correlation coefficient of technical characteristics including content of gross calorific value, volatile matter, moisture, ash and sulfur among the coal mines of Na Duong (Lang Son), Ho Thien (Dong Trieu - QN)
Khanh Hoa (Thai Nguyen)
Thung Than (Nam Mau - QN)
Mong Duong (Cam Pha - QN)
Uong Thuong (Uong Bi - QN). The analytical results show that the correlation coefficient of technical characteristics of coals from various coal mines is not high. The correlation coefficient of gross calorific value R2 is 0,83
the correlation coefficient of volatile matter R2is 0,50
the correlation coefficient of moisture R2 is 0,17
the correlation coefficient of ash R2 is 0,69 and the correlation coefficient of sulfur iR2 is 0,91. The value of the physical characteristics of coal at each coal mine clearly reflects the original conditions of ancient geography, biochemistry and tectonic activity of the Earth's crust.