AM Alaskan Flare and a newbie prospector

[Marked]

Today was the pick of the days weather-wise before I had to be back at work, so nothing was going to stop me getting out with what Santa brought me...

So the kids got up late, dragged their feet, and we eventually got away by 10am.

A two hour drive and we stopped for lunch where I had to drop off a bucket of processed material from last trip (took sooo long to get through panning). A bit of a scout to see if there was creek access further down the road to no avail, and pretty low flow rate saw us back on the main road and heading another 20 minutes away to a slightly bigger creek, where I was sure there would be enough flow to work the Alaskan.

I had done a bit of a reccy here a few weeks before Christmas...but Campers had prevented me getting in to everywhere I wanted to have a look. No such problem today. Still, with a few stops, and a few walks to check track conditions before heading down with the lowered 2wd, and I found somewhere that was just going to have to do and parked the Ford next to a ford. This looked promising as a place to set the sluice up.

The spot I chose to dig sounded wrong in nearly every way to what I remember reading about on this forum and other places...but the clock was ticking pretty loudly in the back of my mind by now...so into the middle of the creek I went, where the water was flowing it's fastest, but also where I could see lots of sand dancing around in the lee of some medium sized river-rocks.

The first attempt at getting some material scooped into a pan was a bit of a disaster, as the flow just swept it out of the submerged pan, but by moving a few of the larger rocks and forming a bit of a deflecting wall, I was able to create a quieter spot where I could fill the pan before getting it to the 1/2" classifier and bucket. I had finer seives with me...but gee I just wanted to get some stuff through that sluice. It was pretty stony stuff, and before long I had worn through the fingertips of the gloves I had with me working the larger stones loose of the gravel and sand. Once the first bucket was full, it felt like I had got down to where there was a bit more sand and gravel than larger stones, so the shovel was employed with the occasional fishing of bigger stones out by hand in order to fill the second bucket.

Back at the ford and leeches removed, I am looking at this flared sluice and the torrent pouring through it, and the buckets of material I just spent an hour scraping out of the creek, and I am wondering if I am about to commit a huge newbie gaff or not. :/ The brief instructions that came with the sluice suggest that the angle on the flare would set the sluice at the correct downward slope...but gee it looked fast. Even blocked up a little more level, that nice "v" shape that forms in the water flowing through the sluice was at the 3rd or 4th riffle.

Anyway, I ran half the bucket (about 5 litres worth of gravel) through the sluice, watching the lighter material suck into the vortexes created by the drop-riffles and dance about before jumping back up to the first little step of the riffle before jumping high enough to be washed down and out the sluice. I vaguely remembered reading Ramjet's Grubsteak thread, so very carefully lifted the sluice out of the flow for a very easy clean-out. I guess I should have run a few pans of the stuff I had dug to get a feel for the difference, but today was all about the sluice. If I had had more time available, I might have also tried classifying a bit smaller and comparing the clean-up materials, as there were quite a few larger stones in the pan. Nevertheless, the first pan was very quick to get down to black-sand level, as the majority of blondes had washed straight out the end of the sluice. It didn't take very long at all to get rid of the larger materials and see the first 4 specks my virgin Alaskan had retrieved for me. I was stoked.

I ran the other bucket and a half, cleaning out at each half bucket, with gold in each clean-up pan. Another two buckets and same method and the kids had just about decided to start the car and leave me...so hole filled in and car loaded up, we headed home. All I need now is to find the right spot to collect material...not just the most convenient.

The photos show just how little I got, but I think the sluice must have done fairly well, as I wouldn't have expected much more from the spot I chose...a 2 1/2' deep hole dug in the riverbed with no bedrock in sight. I had made half an attempt to catch the stuff washing out the bottom of the sluice to check it, but soon realised that wouldn't be possible with what I had with me. I was very impressed with the flour gold that the sluice collected (second pic shows this a little better)...I just wish a few of the specks were as large as the shot-gun pellet it picked up as well.





If anyone who runs an Angus McKirk can tell me how much is too much water, and what size is optimum for material from their experience, I would greatly appreciate it.

 

[Beagleboy]

I think you will know once you use it few times. I have a boss and I clasify material to 1/2 inch and it works fine. I clean up after every 2-3 buckets sometimes even less often. Depends on the flow and how well it cleans up.
Judging by the pictures you got hang of it already.

 

[axeman]

Well done marked, I use a mckirk and setup it up with a 1" to to every 4' drop method and find this works ok. I've only used the sluice a couple of times due to the fact that I haven't had time to go anywhere and the creeks are just water holes at the moment, bloody drought!!!.

One of only a few of pickers I've found.
Mick

 

[casper]

I have a McKirk Recon sluice and find that the slower the stream flow the steeper the fall that is required - try the pebble test initially and make an adjustment if the blondes are not clearing and are choking the bottom 2 or three riffles. i have 1/2 inch and 1/8 inch classifiers and i use them together as a stack. The sluice is faster to clear with smaller gravel - Here is my setup today.....

casper

 

[elbowgrease]

Casper in the picture above, the bottom end of your sluice appears to be sitting too deep in the water. Ideally, where sufficient natural drop in the creek height is not available you want to build up a rock wall so that the exit end of the sluice is not sitting deeper than the entry end whilst still achieving the 1 inch drop per 1 foot of sluice length.

If you can get the angle right without burying the exit end of the sluice you'll find they'll never clog up like you are describing (and what looks to be happening in the photo)

The Angus Mackirk stream sluice series seems to be better in slower conditions of where adequate angle is more difficult to achieve when compared to the AU trap series sluices, however I personally run a Mackirk "Boss" AU trap and find so long as I spend enough time getting the sluice setup right it's unbeatable with recovery and you can feed material through quite quickly.

 

[casper]

Casper in the picture above, the bottom end of your sluice appears to be sitting too deep in the water. Ideally, where sufficient natural drop in the creek height is not available you want to build up a rock wall so that the exit end of the sluice is not sitting deeper than the entry end whilst still achieving the 1 inch drop per 1 foot of sluice length.

If you can get the angle right without burying the exit end of the sluice you'll find they'll never clog up like you are describing (and what looks to be happening in the photo)

The Angus Mackirk stream sluice series seems to be better in slower conditions of where adequate angle is more difficult to achieve when compared to the AU trap series sluices, however I personally run a Mackirk "Boss" AU trap and find so long as I spend enough time getting the sluice setup right it's unbeatable with recovery and you can feed material through quite quickly.

thanks for your helpful insights elbowgrease, it is a lazy stream at the moment and getting the factors just right on the day the photo was taken was more challenging than it was a few weeks ago when the stream flow was stronger.

Casper

 

[casper]

i did some dry testing today and the ancecdotal** 1 inch drop per foot for a McKirk AU Trap sluice equates to a fall of 5 or 6 degrees from horizontal and interestingly when at that angle the feed section at the top of the sluice is level at 0 degrees and that's gotta be designed to work that way i'm thinking..

** it's not mentioned in the basic sluice instructions that came with the sluice

So next is a field test :-

-: ensure a level feed plate (use a cheap level to verify)
-: ensure 1 1/2 to 2 inches depth of water entering the top of the sluice (that IS mentioned in the sluice instructions)

...and we'll see how she goes

casper

 

[Ag Man]

Heya Marked,
That sluice of yours should be able to move a decent amount of material & catch everything no probs.
My McKirk is 1" narrower & 12" shorter & is adequate for my one man operation & am confident it catches it all.
I classify to 1/2" with good flow or less in slow flow.

Wasting time with a spirit level as the sands that hang back in the riffles will tell you if you're level or not. Too much sands on one side? Lift that side up a bit.
Amount of drop required is dependent of the amount of water going thru - just do the 1" (+/-) test & let it roll down without it going gungho.
The more level you can get the riffle section the less chance of blowing any colour out. Less water flow requires more angle, more angle increases the chance of losing colour.

I'm sure you'll have a blast with it.

 

[casper]

Hiya Ag Man

thanks for your insights ....

cheers casper

 

[Marked]

I had a fair bit of 1/2" material just sit in the riffles (tight to the riffle) and never seem to move - new larger material just moved down the sluice, being kept from the vortex zone by the existing material. My feeling was that the fines were still being sucked back into the riffle and falling between the larger material - does this sound like your own observations of operation guys?

Cheers for all the input so far.

 

[casper]

hi MARKED,

I/2 inch stuff should roll straight thru IF you have enough flow.

The basic instructions that come with these sluices say there should be 1 1/2 to 2 inches of uniform flow through the sluice and the water should be fast enough to move a 1 inch rock through.

i classify down to 1/8th inch using 2 stacked sieves now that summer stream flows are weakening...

casper

 

[Marked]

It might have been slightly smaller than 1/2" in hindsight - about the same height as depth of riffle - and they only ever stacked 2 or 3 deep - any extras cleared in short order. Cleanup material was mostly either these, or fines with very few blondes as they cleared from the riffles exceptionally well, making panning a very quick process. I couldn't have got much more water through the sluice, though I suppose I could have used more angle which may have helped clear the riffles better. I will try a few different angles next time I am out when I hopefully will have more time for experimentation. I would have worried if the riffles were clogging with fines as well, though it did cross my mind that the larger material might be keeping some fines from settling at all.

 

[casper]

Be careful not the "sink" the bottom of the sluice like i had done - see elbowgrease's comments above in post #5

good luck

casper

 

[Gavvvvvin]

Tried my Alaskan out for the first time yesterday. Didn't even classify (although I was digging up mostly sand) and it was clearing out massive scoop fulls instantly.

 

[Ag Man]

Too right Gavvvvvvv,
If you got the material & flow right, you can shovel directly in without classifying & can pay off by finding a piece that you may have accidentally classified out had you used a sieve.
My biggest piece to date(spot on 1 gram) was straight off the shovel into the McKirk(sand to 2" sized stuff).
It just sat in the feed tray & didn't move

 

[hardyakka]

Great find there Agman, i've the Boss, its a great sluice, light and easy to clean up

 

[Marked]

Got out again today - had the better half in tow for a day out. Went back to the same spot, and didn't feel so bad about my choice of digging spots as someone else had left a dirty great hole and banker pile about a foot and a half upstream from where I had filled my hole in. There were also little test holes dug in the banks as I waded further upstream, so someone else had had a good hunt around since my last visit.

Under one of these test scrapes, under some overhanging ferns, I found some bedrock jutting out into the stream bed, so decided to have a go there. The river-stones and gravel were jammed in pretty tight, so I was feeling confident no-one else had dug here in ages - but the first two 10 litre buckets produced little more than half a dozen specks; most only flyspecks. Similarly, the 3rd bucket produced but a couple of tiny specks. I was finding I had to dig by hand and trowel, as the shovel was doing nothing against the hard-packed material, and I had started filling the waders up at this stage as I leaned down to where I was feeling a bit of a ledge in the decomposing bedrock.The last 2/3 bucket full was of material from this little ledge and what I could scrape out from under a little overhang that I found at this depth. A couple of larger bits (still not picker size) did come out of the top of the bucket when I was running it through the sluice (so the deepest material) but also making an appearance on the feed tray was a shiny copper rivet of some sort...so much for my virgin hole.

My little under-water crevice seemed to extend further under the rock...my tyre-lever nearly diappeared when I was having a bit of a poke around...so a return might be worthwhile with a crevice-sucker. Either that, or I just need to head further upstream.