SELENIUM is a highly dispersed element with a lower Clarke of 0.05×10~(-6) and rarely forms its own independent deposits in the crust. In recent years by the discovery of a series of selenium-bearing deposits(such as Laerma selenium-gold deposit and Yutangba selenium deposit) and selenium-rich strata (westHubei, Laerma, Ziyang, Langao, northwest Hunan, etc.), the character and genesis of the seleniumbearing formation (SBF) have been noted by many researchers. 1 Some classical SBF in China In China the classical SBFs include: (i) The Lower Cambrian SBF in Laerma, west Qinling: Thebackground value of selenium is 5.47×10~(-6), and the selenium content of the sillcalite and slate (mainrock type) averages 8.70×10~(-6) and 3.05×10~(-6) respectively. (ii) The Lower Cambrian SBF inZiyang and Langao, east Qinling: Selenium is present in relatively high abundance in the SBF, averaging3.89×10~(-6) in the slate, 2.86×10~(-6) in the sillcalite. (iii) The Lower Cambrian SBF in northwest Hu- SELENIUM is a highly dispersed element with a lower Clarke of 0.05 × 10 -6 (6) and less forms its own independent deposits in the crust. In recent years by the discovery of a series of selenium-bearing deposits (such as Laerma selenium- 1 character classical SBF (gold deposit and Yutangba selenium deposit) and selenium-rich strata (westHubei, Laerma, Ziyang, Langao, northwest Hunan, etc.), the character and genesis of the seleniumbearing formation (SBF) have been noted by many researchers. in China In China the classical SBFs include: (i) The Lower Cambrian SBF in Laerma, west Qinling: The background value of selenium is 5.47 × 10 -6, and the selenium content of the sillcalite and slate (mainrock type) averages (Ii) The Lower Cambrian SBF inZiyang and Langao, east Qinling: Selenium is present in relatively high abundance in the SBF, averaging 3.89 × 10 ~ (-6) and 3.05 × 10 -6 (-6) in the slate, 2.86 × 10 ~ (-6) in the sillcalite. (Iii) The Lower Cambrian SBF in northwest Hu-