Burdie, everyone seems to have they're own methods, so I'll only comment on what I do.
First, classify to remove larger rocks and do so carefully, watching for nuggets as I go. I pan whats left down to the black sand and only pick out any nuggets I happen to notice. Then everything goes into a bucket to finish up on later, either when I get home, or when its raining to heavy, etc.
I get a shallow plastic container, (such as a plastic gold pan), ready by filling it with enough water to nearly fill the container or pan, and add a small amount of water softener, (its cheap and goes a long way), to break the surface tension of the water, (left out afterwards, this becomes a deathtrap for mosquito's). Then I take the concentrate from the bucket and pour it a cup or so at a time into the shallow plastic container or pan.
At this point, we go high tech and build a proper iron, (black sand), removal device using a pill bottle and small but strong magnet that fits across the bottom of the pill bottle. Drill, or cut a small hole in the top of the bottle and connect a string, or piece of wire to the magnet and have the string, or wire thread through the hole on top so that it can be attached to a piece of plastic, (a pull tie works), or a key ring. The idea being, that when you lift out some iron, (black sand), and move the magnet over the container you want to deposit the iron into, you pull the ring on top, lifting the magnet away from the bottom of the pill bottle and the iron drops off.
And after gently shaking the pan and swirling it to get the gold on the trailing edge of the swirl, I hold pill bottle about 1/4 to a 1/2 inch above the iron and lift off small amounts at a time, until no noticeable amounts of iron lift off. Don't let the bottle come in contact with and disturb the concentrate, as this will cause it to lift some black sand that contains gold and has just enough iron to be attracted to the magnet. If you want to be sure you have all you can get at this point, then re-swirl the container, or pan and repeat.
I don't have a mercury retort anymore, as it was stolen along with most everything I owned several years back, but thats another sad story. I do hope to get another one as this next step is more safely done with one. If I had a mercury retort, I would dry the remaining concentrate and heat it in the retort, just in case there is some mercury in it. But, since I don't have one, I use a normal cast iron frying pan with a loosely fitted lid and heat for about 15 minutes on a propane burner well away from myself, or any other living thing. This is done to remove, either, or both, mercury and sulfides.
Once the contents are removed from heat and allowed to cool, you can again swirl the contents in a pan, (you can do this dry), and use a snuffer bottle to draw off any gold flakes, or small nuggets. A good pair of surgical type tweezers are good for this too.
At this stage you should have at least one proper beaker. They sell for only a few dollars and are well worth the investment. Read over the following page and when you get to the bottom part titled "Dealing with black sand", you will have all the info you need for dealing with small amounts of black sand.
http://www.prospectorsparadise.com/html/acids.html
One last thing. I know I'm repeating some of the advice on the page above, but get protective gloves, goggles and apron for use with acids. And work outside in a well ventilated area away from people, pets, or other distractions.
Good luck and be safe.
F.
