Oil and gas companies were among the biggest risers on the FTSE 250 index on Monday, tracking a rise in crude prices. Independent oil and gas exploration company Heritage Oil ended the day higher while shares in hydrocarbon producer and explorer Afren were also up at the close of trading. Meanwhile, shares in Egypt-focussed gold miner Centamin lifted on a day when gold traded higher. The Forex Gold Index was up 8.0% to 1402.50p at 15:00 on Monday.Fallers on the index included platinum mining company Lonmin. This coincided with multiple media reports that a unionist had been killed and another wounded at a Lonmin-owned mine in South Africa. The BBC news website claimed that the National Union of mineworkers had said that a shooting had happened near the town of Marikana, north-west of Johannesburg.FTSE 250 - RisersHeritage Oil (HOIL) 146.90p +3.52%Afren (AFR) 135.10p +2.97%Stagecoach Group (SGC) 301.90p +2.06%Paragon Group Of Companies (PAG) 306.90p +1.99%Carpetright (CPR) 623.00p +1.80%Ashtead Group (AHT) 641.00p +1.58%Centamin (DI) (CEY) 39.03p +1.53%Kentz Corporation Ltd. (KENZ) 404.70p +1.50%Hansteen Holdings (HSTN) 89.65p +1.41%Premier Farnell (PFL) 216.00p +1.36%FTSE 250 - FallersLonmin (LMI) 281.40p -4.61%Oxford Instruments (OXIG) 1,614.00p -4.10%Persimmon (PSN) 1,170.00p -4.10%Dairy Crest Group (DCG) 467.80p -3.80%Halfords Group (HFD) 316.60p -3.77%Intermediate Capital Group (ICP) 451.10p -3.61%Mitie Group (MTO) 251.10p -3.39%Taylor Wimpey (TW.) 95.80p -3.38%Hochschild Mining (HOC) 246.20p -2.92%CSR (CSR) 536.00p -2.90%MF