John
I doubt seriously that you located a honey mesquite that large. They seldom reach 1' in diameter. While I am not calling it impossible, far more likely is the probability there is a slip in ID.
Velvet mesquite routinely gets to 2' and that is where smart money would go...
In the real world it makes little difference which it is. Screwbean is the stock wood of choice among the mesquites even though it is the smallest mesquite... And the smallest tree recognized as quality stock wood. There are reasons...
Assuming it is velvet the biggest chunk of wood is likely underground. It is probably the most highly figured and colored, too. Right now, before doing anything else, go paint the end of the stump with anything you have on hand that may slow weathering on the end grain; Old latex paint, oil finishes, anything will help...
Screwbean shines as stock wood because it is incredibly stable and mechanically a lot tougher than woodpecker lips. The fact it can be gorgeous is another asset.
Regardless which it is the stump is probably worth digging out and saving... If masochism is your thing!
First buy a new chain saw and kiss it goodbye at the store and tell yourself to not get attached. Buy a bunch of ripping chains while you are at it.
Disabuse yourself immediately of any fantasies involving milling the stump. No sane person would consider cutting a stump on a mill. Being around insane people with sharp objects is bad ju-ju...
First dig out as much stump as you can, exposing it as deep as possible. The best stocks have grain which follows the sweep of the wrist and that comes from crotches and root swelling usually. Fortunately mesquite has almost no rotting issues. Make the first cut radially from the center of the tree out to the largest lobed root you can expose. Actually the cut should be parallel to that line and an inch or two to the side.
Do not worry about cutting up the center of the stump because the "core" area is "juvenile wood", which is short-fibered, erratic acting and frequently stressed.
Make the second cut parallel to the first and 2 1/2-3" away.
Go to the saw shop and buy another chainsaw bar because you should realize about now a plunge cut is required and it is much deeper than the bar any sane saw comes with. You may as well look at buying chain in bulk to replace the half-dozen you have ruined with the rocks in the first two cuts.
Make more cuts around the stump, each time looking for what looks to be the best prospect in your mind's-eye. Eventually some of the lines will connect and you will see how to cut a blank free. Subsequent blanks will come off much easier because of the access granted by the first blanks.
Coat as much figured surface area as possible with anchorseal, melted paraffin wax, log oil, anything to slow down drying. Drying wood is not actually about getting the water out, but rather getting it out slowly enough to prevent drying defects and fast enough to prevent rotting.
If Castwell is in humid TX you may not need to cover the blanks, but if it is real dry or hot there, a tarp will be needed to slow the water loss. A layer of stickers is required on the top of the bunk to keep the tarp from touching the wood and inducing mold, or sticker stain as it is called.
Getting the wood dry is not a problem and it happens faster than it should in most cases, but aging a stock blank is a different matter. Each time the wood cycles down into dry it and back up to the 12-15% range it relaxes internal tensions (and compressions) and the more the better. Most stock makers do not like wood less than 5 years old and many are far fussier. Premiums are charged for really old blanks of quality...
When looking at the tree and deciding where to cut the blanks you should always think in terms of which is the best in the whole stump and cut it out first. You will make mistakes, but the more you cut the more you will see where the best stuff is.
The inside curves of root swellings will have curl radiating from the outside in. Feathers are from crotches and best displayed by cutting a crotch to look like two open "Y"s. The feather will be right at the bottom of the ditch and running straight down. In root wood feathers occasionally show up pointing straight up into the tree but are seldom long, just adding some wildness to the very butt.
Always cut as deep as you can.
Throw away the saw...
art
