Shares were lately up by almost 11 per cent at 52 cents, earlier touching as high as 56 cents.
The company said late last week that the mineralization within its first NI 43-101 compliant resource estimate at its Olza project averages about three metres in thickness.
The miner recently released the zinc-lead resource estimate at the project, a 100-square kilometre property located in the Upper Silesian mining district of southwestern Poland, an area of extensive Mississippi Valley-type deposits in which zinc-lead mining has taken place since the 12th century.
Rathdowney noted that mineralization at the project occurs along a corridor with a total strike length of approximately 10 kilometres and width of up to one kilometre.
Within this mineralized corridor, Rathdowney said it defined a mineral resource using holes from historical and recent drilling.
At a 2.0 per cent zinc cutoff, these inferred mineral resources stand at 21.2 million tonnes grading 7.42 per cent combined zinc and lead - or 5.88 per cent zinc and 1.54 per cent lead.
Last week, Rathdowney said the estimate showed "clear potential to add substantial resources and make new discoveries."
The results, based on 780 core holes drilled historically by the Polish State as well as confirmatory drilling in 175 core holes carried out by Rathdowney since June 2011, represent the first estimate carried out under modern standards, in compliance with Canadian regulations.
Rathdowney is focused on finding and developing zinc-lead-silver deposits in the ore fields of Europe.
The Olza project is near a state-owned zinc smelter complex that is expected to have additional smelting capacity when the Pomorzany mine in the region closes in the next three to five years.
The surrounding infrastructure at Olza, as well as the expected increase in zinc prices as supply wanes over the medium term, bodes well for Rathdowney Resources and the development of its Polish property.