This particular vein is only about 25' from the adit. Now, they went pretty far back with at least one vertical shaft and skipped this one, so I don't imagine they found it worth mining.Take a chip sample perpendicular to the strike and dip of the vein. Chips should be of an equal quantity from across the vein. This technique is used if you are going into production mining, where you will be mining and milling the entire vein. Costs to mine wide enough to get your butt through and work in some degree of comfort, should be calculated into total costs.
If you are specimen Gold mining, that is another ball game. Some high end specimens will pay much better then mining a narrow medium pay vein. There are a lot of logistics to making money in the mining business.
If there is decent Gold in a narrow section of the vein, you will still have to calculate for at least a 4' x 6' heading in costs to drill, blast, muck, timber, mill ,and remediate any water quality issues which may arise, and abandonment procedures.
Or at least I think. To the right of this vein is a collapse all the way to the surface where the vein is exposed. I cannot tell if they had a storage space that was unsupported causing the collapse to the side, or if they were starting to go after this vein. It definitely has gold, albeit not much from my samples. It's a tricky spot because it's accessible, but potentially unsafe with the country rock to the side compromised.
The mine is only 30 years old and was owned by two brothers who did pretty well, hitting at least 4OPT but I also heard up to 10. I cannot get back past the collapse until the spring melt when I can muck it out and retimber it. So in the mean time I'm playing with this one. With the easy access, I was thinking I could just target the top half if that's where all the gold is. Just to get started and get some gold in my pocket before putting a lot of money into it.
It looks like I need 8x8's, so I'm looking into cutting my own timber.
Here is a picture standing in front of the vein picture I posted looking to the right, and a picture from topside.