So a true width of 6.8 and it extends up dip about 50 meters to...

So a true width of 6.8 and it extends up dip about 50 meters to the next drill hole of around 1 meter at 3 grams a tonne .
There is also an assumption you have made that the drilling is being done 90 degrees to strike where in fact it could be oblique to strike, that assumption is fine as we do not really have enough info on the strike angle of orientation at the point of drilling to determine if it is oblique or not .
By looking at the drill core that could be determined if it is stratabound so what angle the drill is at to the strike (Springer, Economic evaluations in exploration page 23) .

Above that 1 meter at 3 grams intersection I doubt it would be economic to hard rock mine(based just on that sectional view) as too high a dilution for what already is a low grade
So (6.8 +1)/2 = 3.9 meter average thickness
50 meter height
looks to be around 200 meter strike length
SG3 (guessing)
3.9m * 50 * 200 * 3 = 117K tonnes

Then would need to do the same exercise for the other lodes ie velvet to take out the "fudge factor" taking into account a lot more drilling is needed to firm it up .