Tertiary Minerals PLC (AIM:TYM, OTC:TTIRF, FRA:TMU) said it is preparing its largest Zambia drilling programme to date as it looks to convert the Target A1 silver oxide discovery at Mushima North into a maiden JORC Mineral Resource Estimate by the end of the year. The AIM-listed explorer plans around 4,000 metres of reverse circulation drilling, with work expected to start within the next two weeks.