Zircons were separated, using standard heavy liquid and magnetic techniques, from several kilograms of crushed rock.
The results have been converted into kilograms and centimetres.
On a typical trip lasting eight hours, this result implies an additional catch of almost 6 kilograms of fish.
The total volume of exchange is therefore the simple product of population per phase and kilogram of obsidian used per person per year.
A limit of thirty kilograms becomes almost unacceptable for large works.
Five kilograms of cobs from each plot were dried, shelled and the g rain yield deter mined after adjustment to 13% water content.
To pay their dues, rent and taxes they had to sell 600 kilograms of grain, or in other words, 10 per cent of their harvest.
Again, this would mean about 5 kilograms more fish per day for an artisanal fisherman.
