Petmin non-executive director Enrique Greyling has invested nearly £41,000 in the anthracite and silica miner. This deal was originally mistakenly reported as a disposal. Greyling has bought 156,000 shares at R2.95 (26p) a share. Greyling owns just over 3.67m shares. His fellow directors have also been buying shares in recent weeks. Chief operating officer Bradley Doig has invested nearly £139,000 and deputy chairman Lebo Mogotsi has spent £148,000. Greyling was appointed to the AIM-quoted and JSE-listed company's board in February 2004 and is a non-executive director of a number of Petmin subsidiaries. He is a former board member of the Banking Council of South Africa.Petmin produces 1.4m tonnes of silica a year from SamQuarz plus anthracite from Somkhele. In September, Petmin declared a maiden dividend of 6 cents (0.53p) a share along with its figures for the year to June 2010. The dividend is covered more than three times by earnings. Revenues were sharply lower in the year to June 2010 but margins and underlying earnings per share both improved. Sales of anthracite and silica were both well down on the previous financial year. Top Director BuysPentagon Protection (PPR) Director name: Mr Haytham ElZaynAmount purchased: 80,000,000 @ 0.25p Value: £200,000Babcock International Group (BAB) Director name: Mr Archie BethelAmount purchased: 27,634 @ 576.00p Value: £159,172Petmin Ltd. (DI) (PTMN) Director name: Mr Enrico de Villiers GreylingAmount purchased: 156,000 @ 26.00p Value: £40,560Spectris (SXS) Director name: Mr Russell J KingAmount purchased: 3,000 @ 1,182.00p Value: £35,460Top Director SellsFerrexpo (FXPO) Director name: Mr Michael AbrahamsAmount sold: 58,310 @ 381.00p Value: £222,161Babcock International Group (BAB) Director name: Mr Archie BethelAmount sold: 34,000 @ 573.00p Value: £194,820