The actual production of ironwood does not match the description of the item (which says "ironwood [IRWD], weight 10. Units with lumberjack [LUMB] 3 may PRODUCE this item at a rate of 1 per man-month."). A lumberjack with skill 3 produces 3 pieces of ironwood per month. I do not know which is correct. Please ask Loriaki for further details.