Ann: New Gold Discovery, page-27

main factors for the grade particularly when comparing to historical grade will be dilution and hand sorting.
Back in the old days mining these narrow ore body's they were both able to mine with next to no dilution and use hand sorting so only pure ore was processed.
This makes it very difficult for us or any other historical mine to achieve the same grades even when mining the same ore as we have to mine wider and take more waste which can't be removed.
Another factor is how wildly the grade of the ore can change over a very small distance, you can have a drill hit of 20-100 gpt+ but when you get their and mine it the average will be lower as the drill result was influenced by spotty nuggety gold that is generally only peppered through the ore.
Also while we get these very juicy high grade bonanza areas the ore can just as quickly turn back too ten gram or less dirt. This is a feature I saw first hand at the morning star where they would be chasing a 20-30gpt drill hit but mine through low grade ore to get to.
Narrow veins can go from 30 gpt to 5 over as little as a couple meters which is why we can't get a jorc resource out for the A1.
Regardless of what I have said the fact remains they are mining it profitably and taking good measures to increase the rates and margins.
Overall the A1 seems to have good quality ore body's, better then morning star which also had a historically average grade above 20gpt but could not even come halfway to replicating that in the modern time.
In summary narrow orebodys are inconsistent by nature making mining and good long term operation difficult but certainly not impossible. Only need one good bonanza patch and cash build should be very strong hopefully