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The Hand Held Torch Assay


Although the major mining companies don’t shout about it, it’s a known reality that most ore deposits were found by individual prospectors. Sometimes beginners luck played a significant role, but this method of locating a discovery is becoming harder to accomplish.

Personally I believe that prospecting is a calling and not a profession. Unfortunately, ignorance commonly dooms the desired outcome. So, whether or not the prospector has a formal or rudimentary knowledge of chemistry and geology this natural instinct must be cultivated. To put this perspective another way, the prospector needs to hone the senses to recognize when in the proximity of success.

Because geology and chemistry are constantly evolving concepts they should not be relied upon for recognizing a potential discovery. In fact, the concept of prospecting is pioneering and seeking new understanding of the truth that is constantly in front of the eyes, but cannot be seen till the right pair of eyes comes upon that which has waited patiently since the beginning of time.

Historically, prospectors had to contend with the forces of nature, roving bands of hostile natives and gangs of bandits. Sadly, the situation hasn’t changed much. Although modern conveniences have tamed nature somewhat there remains those who despise man’s quest and use of metals, as well as all the king’s men who constantly claim the natural resources are theirs and will go to unbelievable ends to maintain their dominance. Consequently, prospecting remains relegated to or for those foolish or brave enough to venture into the unknown.

It goes without saying or is amazingly understood within the community of prospectors that this craft seeks understanding the mysteries that rocks contain. But, the paramount challenge is being able to decipher the cryptic messages of rocks if the prospector is to survive the ever-shifting challenges. Therefore, the question inevitably becomes – how to reliably accomplish the feat of unlocking these mysteries and obtain metal in hand? “Metal in hand” is the only proof worthy of discussion, all else is questionable conjecture. And, as a friend reminded me – obtaining the metal in hand must be done at least 3 times. To this end I constantly strive, and every once in a while I am flabbergasted when upon the 4th attempt and following the same procedures I fail to get the desired metal. When this happens, usually it is because of some foolish unintended procedural error was committed. So, strive for quality in the effort.

Prior to embarking on the prospector’s path of wild expectations there is no substitute for homework. Maybe the novice mineral hunter will find a glory hole on the 1st day and not have to know anything about assaying. However, this is highly unlikely and if homework was not done prior to a discovery it will become a requirement before or soon after staking a mining claim that is not based upon wishful thinking.

The more a prospector knows about his terrain and rocks the better equipped he will be to reap rewards. With this reality at the forefront of awareness the one thing a prospector has an abundance of is questions, which can only be answered by study that only homework will satisfactorily conclude. Although this course has many attributes, facets and variables, the focus is how to apply a simple cost effective method of assaying. Having said this, I add the caveat that what follows is not complete nor meant to circumvent traditional assaying procedures, but, instead, is being offered as a supplement to the over-all quantity of homework.

The simplicity of implementing this assaying procedure is why I enjoy it. Learning how to accomplish what is normally hidden from prying eyes will aid in applying flux formulations for traditional fire assay techniques that will ultimately follow these preliminary footsteps.

The beauty of this type of testing is that fluxes are not always a requirement. In fact, I prefer to not use any fluxes till I have exhausted the possibilities that a mineral will not give-up any metal. Then, if no metal is easily reduced I resort to using sodium carbonate, which often allows for metal reduction. If these trials fail then use of the common fluxing agents becomes a necessity.

Keep in mind that the propane and Mapp gas torch flame is a too concentrated heat source to adequately fuse a 30 gram sample with fluxes. Consequently, modifications have to made, such as limiting the amount of mineral to be fused. In fact, it is best to begin any and all tests with very small (1 to 5 gram) samples and if any pleasing results are obtained conduct alternative testing procedures.

Normally the prospector is after one or all the precious metals. Trouble is – seldom are precious metals casually lying around to be easily identified. As a result, some type of assaying must be used to determine if the sought for metals are present and how to efficiently extract them. When metal is obtained with this poor man’s methodology it is not only an enjoyable moment, but tangible proof that the endeavor is worth further study.

While obtaining the precious metals is exciting – the other side of this spectrum lay all the other metals, which may be far more valuable than all the gold and silver in a suspicious rock. So, it behooves the serious prospector to examine all suspect rocks for the common base metals, from which most of the precious metals are extracted as by-products.

Feel free to ask questions.

Joseph Cummins


Created: 04-08-2007


Making Clay Containers

History indicates that the fire assay begins with a clay pot. Therefore, clay is the 1st topic of discussion. Try to keep in mind that although I think what I am trying to pass on is credible, the following visual homework course won’t find endorsement by professionals and academia. Nevertheless, the consequences of not being able to conduct these down-to-earth types of inexpensive tests will likely create a shallow grave for the normal modern mineral seeker.


There are several types and mixtures of clay. Of course, it goes without saying that the purity of the clay is also important to avoid possible contamination during fusions and at same time maintain the physical integrity of being a container.

Over the course of time I’ve conducted tests to see if the clay harbors gold & silver and no evidence of Au & Ag contamination has been found. Nevertheless, it’s wise to always be on the look-out for any possible unintentional salting. I try to purchase name brand clays that potters use, which made be a little more expensive, but have the mark of time tested acceptance invisibly stamped within this mineral, which can also be a profitable prospect to locate.

The primary purpose of making these small clay containers is to determine if reducible metals are present by utilizing the hand-held torch as the heat source instead of the typical furnaces.


I like the clay to barely cling to my fingers and hands as I massage and form it to a desired shape and size.
I use a wood base to place the clays dishes upon, which slowly absorbs moisture, making the drying time faster.


The fingers can form just about any conceivable form. But, keep in mind that some forms of pots may not be amenable to the torch assay, such as the 3 at the top left of this image.

The clay dish at 9o’clock is a commercially made scorifier, which has a semi-glazed and smooth interior. The normal commercial clay dish costs about 5.00 each, so it’s apparent that considerable savings can be had with a little patience and practice making these dishes. Furthermore, although I do spend considerable time making these dishes, for a few pennies each, I also am no longer at the mercy of the merchant and have the flexibility of creating what I think may be needed to complete the task.


Pictured here are a few more clay dishes of differing shapes and sizes being used for a specific test to see what type of configuration is best.

The 3” diameter dish at bottom left is commercially manufactured.

Personally, after years of making my own clay dishes for torch fusion tests I prefer them to the expensive commercial quality. Furthermore, other than a potter I don’t know where very small or odd sized dishes can be purchased.

I’ve found that 20 pounds of clay (20.00) will normally make between 250 & 600 dishes, similar to what has been shown here.

After making a batch of dishes they are allowed to dry for at least 2 weeks. When thoroughly dried I stack them in the electric oven and fire them. Depending upon the over-all sizes I can usually fire about 50 dishes at a time. These 50 dishes usually last me a few days of intensive assaying and I try to always have a couple hundred on hand. Of course the weather is a significant factor, because this type of assaying is an outdoor activity.

Some type of high temperature furnace is needed to fire the clay to make them able to withstand the rigors of assaying. If the prospector does not have a furnace usually somewhere close by is a potter who may be willing to fire these home made pots.


Stacking dishes in this manner allows for the greatest quantity to be fired and they do not stick together. However, it is wise to coat the bottom of furnace with loose bone-ash to make sure the clay does not intermingle with any contamination on the furnace floor.

This image illustrates that the electric heating element is about ready to bite the dust, that I keep patching trying to get the last bit use from. Roasting sulphides will cause the heating elements take to begin to break apart due to the corrosive properties of sulphur.


The electrical heating elements becoming red hot.

Normally, the full electric oven is turned to lowest setting for an hour, then the heat is gradually raised every half hour till the dishes are red hot. I’ve taken the dishes to yellow and almost a yellow-white heat, but found that this higher heat serves no useful purpose of maintaining clay dish/pot integrity during fusions.

Getting the oven too hot will cause some clay to slump, semi-melt or become deformed.

Grinding, Screening & Concentrating



Minerals must be pulverized before most fusions. Trying to fuse large hunks of minerals has some limited use in sublimation tests, but seldom for a melt. Furthermore, mineral fragments larger than 1/32nd of an inch have a tendency to explode due to entrapped water that becomes steam.

I use only ceramic mortars and pestles to avoid introducing contaminates. Prior to grinding a small rock fragment I thoroughly pre-clean the mortar and pestle with water, then wipe with clean paper towel, then soak with HCl or HNO3 or a combination to be sure that no unintended contamination occurs to cause me anguish later. It is better to begin with as many knowns as possible, thereby reducing errors later or worse too many questions, which necessitate re-running the same fusion over again, assuming that careful notes were kept to be able to duplicate the test.

Years ago I quit using the typical Iron Mortar & pestle due to introducing metal shavings and contaminates the mortar may have clinging to walls and trapped in the bottom. Cleaning these Iron pots is really difficult and using acids is almost pointless.

During the grinding process, knowing the particle size before proceeding to the fusion stage is extremely important. So, specific sized screens are employed to know exactly what size the mineral will be. It is really easy to say – what the heck – and not go to the time consuming aggravation of screening, but for me knowledge is crucial.

I have settled upon a screen size of 150 mesh. Having said this it should be kept in mind that screened mineral fragments might be larger in one direction than the other. Here are a few typical screen sizes.

10 mesh = .0787 in.
20 mesh = .0331 in.
40 mesh = .0165 in.
80 mesh = .0070 in.
100 mesh = .0059 in.
120 mesh = .0049 in.
200 mesh = .0029 in.
325 mesh = .0017 in.

74micron = 200mesh
53micron = 270mesh
37micron = 400mesh
20micron = 625mesh
10micron = 1250mesh
5micron = 2500mesh

A 40 micron particle in a gold pan is at the limits of what the human eye can see.

Often it is useful to utilize 2 or 3 stacked screens, which could be 80, 100 & 200 mesh and run fusions on each portion, as well as conduct microscopic examinations to help determine when mineral liberation occurs from the undesirable portion of rock. Grinding to any mesh size finer than 200 is exceedingly difficult and time consuming and unnecessary for this type of testing.


It is normally beneficial to concentrate the heavies from the light minerals with the typical gold pan. Usually concentrating is done after screening, which helps determine the quantity of the sought for minerals from the waste portion of rock. Although total liberation of ore is the desired goal, it is usually unobtainable.

After screening the next phase is to blend the sample for uniformity, then weigh the amount to be assayed.


Sometimes intentional salting – known as inquartation – with silver and/or gold is desirable just prior to a fusion for the purpose of possible collection of additional precious metals.

Ascertaining the size/amount of the inquart is important to know whether or not some amount of the inquart was lost or hopefully gained during the fusion. This can be accomplished by weighing or measuring the inquarted bead.

Most prospectors cannot afford a good scale that can weigh fractions of a milligram, so using a digital caliper or optical measuring device becomes essential if the amount of goodies is to be reasonably determined. Equally important to knowing the amount to be inquarted is the purity of the inquart.


Picture illustrates a polypropylene calibrated pipette dispensing a measured amount of silver nitrate solution (inquart) to a pulverized mineral just prior to being fired with torch..

Many assayers will use a solution of silver nitrate that has a known ratio of 1 milligram per milliliter. But, even though a silver nitrate solution can be purchased or easily made the purity is always in question.

To assure purity, I go to the trouble of digesting silver bullion (stamped 999 or 9999) in nitric acid and water. After all the silver has dissolved I filter it 2 or 3 times and place the beaker with solution on hot plate to drive off all water. Note: In the final stage of drying silver nitrate the heat from the hot plate should be at a very low setting to avoid the silver nitrate catching fire in the beaker. The almost dry silver nitrate is then converted to metal, which is then poured into cold distilled water to give me a bunch of different sized pieces of silver. These small pieces of silver are placed in pre-dug cavities on a plaster of Paris tablet.


With the pieces of silver positioned in small depressions carved into the plaster they are melted with a hand-held propane torch flame that drives off volatile contaminates, such as Lead and Bismuth. The sublimates of yellow, red, blue and green indicate contamination, whereas the brownish (tan) color is the typical formation of silver oxide.


This plaster of Paris tablet with various sizes of now mostly clean silver beads are ready for future inquartations.

Typical small non-commercial assay furnaces

Prior to and during assaying emphasis should be on keeping well organized notes regarding the specific mineral sample, date, circumstances, anomalous occurrences, as well as taking pictures of the procedures. Not only will this data become helpful for future fusions, but may be invaluable for protecting a mineral discovery.

The art of fire assaying has it roots deep into the past and utilizes the time honored flame, as well as today’s electricity. Although I’m emphasizing the hand-held torch, I am making a quick overview of the typical gas and electric furnace for those who are unaware of the basics.


This image is depicting a propane cylinder, connecting hose, firepot connected to a small shop vac that provides forced air. The mixture of gas and air creates high temperatures needed to melt metals and minerals with common fluxing chemicals usually contained in a 30 or 40 gram clay or graphite crucible.


The hole in removable lid provides an escape route for hot air. Although this fire pot is for crucible fusions cupellation can also be done although not the best environment.

This next image is of a small electric furnace, which I use for crucible, small clay dish fusions and cupellations.

The small clay pots pictured on top of electric furnace was an experiment I ran on a sample. I had crushed, screened, concentrated, blended, split and weighed a rock sample to be assayed in a variety of pre-fired clay vessels to see what type of container worked best at obtaining metal. No fluxes were added in this particular test, although fluxing agents are usually employed to achieve a good melt, as well as metals.

The top left dish was previously subjected to a propane torch flame and some metal was reduced, but because of encountered problems I decided to complete the fusion in the furnace. The taller cylindrical pot at right has a lid.




The dish at left.is Beginning to melt.


Leakage of the previously heated clay dish is noticeable, but to avoid thermal shook to the heating elements, which reduces the useful life and not wanting to cause problems with the other fusions I allowed for what is seen next.


The clay pot that I had previously melted some of the mineral in broke apart due to cracks that I thought would survive intact, but did not. The white material on the furnce floor is powdered bone-ash, which helps absorb molten spills.


It is visibly evident that the melt expanded and tried to run over two of the clay containers. Slag colors can be useful in making determinations for future assay procedures as well as determining major minerals.


Each clay vessel contained a 1 assay ton (29.1 grams) charge, that had been thoroughly pre-blended and split, so nearly identical circumstances were at play during the fusion.

Although this posted image is small, it nonetheless provides visual evidence that pot configuration can play a crucial role in the outcome. Thus, another reason for making clay dishes and not be confined to traditional commercial crucibles.

The center vessel produced the largest quantity of reduced metal(s). The vessel at right was a failure and the dish at left has a metal button, but is about ½ the weight of the center pot results.

The hand-held propane, Mapp or oxygen & acetylene torch

Although this next image illustrates using red Lead oxide in addition to the mineral all manner of procedure with and without fluxes the torch assay can be fruitful in determining what a rock may contain.

I’ve found that just because one or two tests fail to produce desired results it does not mean that reducible metal is not present. So, it behooves the prospector to experiment or change course, which is not much different than the normal procedure of prospecting.

Regardless of the numerous gadgets, widgets, myths, tales, mystic mediums, witching sticks, dowsing rods or high hopes at some point metal in hand will be the ultimate determining factor for all future activities.


No matter what kind of or the amount of mineral, with or without chemical additions I always put the mineral in the clay pot prior to heating. This allows the pot to not get too hot too fast, thus avoids too much thermal shock to the pot and at same time the mineral is being heated. Another nuisance that can occur due to heating the clay too fast in one spot is that a small portion of the clay will explode and detach. So, slow and even preheating is mandatory to avoid unwelcome surprises.

I always begin by gradually heating the bottom of the clay dish. I constantly turn the vessel to be assured that even heating is taking place. And when the vessel gets too hot for the fingers I either put a glove on and continue heating the entire outside of pot or begin allowing the flame to carefully make contact with what is to be melted.

If the flame is too large there will be too much force and will blow the contents out of the bowel, so I usually try to heat the contents slowly and gradually increasing the flame size as surface melting occurs.


This image illustrates the slow oxidation and melting of the red lead oxide surface. If whole wheat flour in mixed with the litharge (lead oxide) some Lead will be reduced. In fact some Lead is reduced due to a low intensity flame (blue portion), which has a reducing nature.

Continued heating gradually produces melting of the Pb3O4 (Red Lead oxide or litharge), which begins to combine with the mineral.



The melt is finished and still almost liquid. Some cracks have formed, but normally these cracks do not create problems, nor do these cracks penetrate through the clay. However, if initial heating was too fast the cracks can cause the dish to fall apart. Practice is the only way I know of to learn what is ok and what is not. Mistakes are unavoidable and often necessary in order to learn.

The next step is to break the clay dish and retrieve any metal for cupellation. It also may be necessary after breaking the dish to crush the slag to retrieve small pieces of metal that did not accumulate into a single mass. A new smaller dish will then be used to fuse/melt all collected metal particles.

Many minerals without fluxing agents will defy being melted with the propane or Mapp gas torch. When this occurs I use the oxygen and acetylene torch, which I have come to rely upon almost exclusively.

The traditional oxygen/acetylene torch is expensive (300.00 to 1000.00), and may be beyond the financial means of most prospectors. In this case the alternative may be to occasionally use a friend’s torch. Another alternative available is a small complete torch system found at many hardware stores for about 50.00. This last potential torch has the decided advantage of being very portable and useful, but the gas canisters are about 8.00 each and the oxygen only lasts about 5 minutes, which can be considered expensive.


I always use the propane torch to preheat the clay pot prior to using the oxygen & acetylene torch.


Obviously the tip is becoming contaminated because the flame has become distorted. Sometimes volatile minerals cause constant tip cleaning with this or even the propane torch. Even though this volatilization is a nuisance it is also a valuable visual clue that some type of element is being lost


Applying the proper quantity and intensity of heat comes with practice.


How close the tip is to the molten mineral is a matter of experienced judgment along the learning curve.


I cannot rely upon memory, so when conducting multiple assays I place pieces of paper with notations so I can later identify and make my notes about the results.

Melting silver


This chunk of silver originated from silver bullion that I dissolved in HNO3 & H2O, vacuum filtered, semi-dried and the resultant AgNO3 was melted and poured into a bucket of cold distilled water and re-melted in a clay dish with borax to absorb some potential impurities.

It is reasonably easy to melt small amounts of silver with either the propane or Mapp gas hand-held torch. However, large amounts of silver require the aid of oxygen with propane or acetylene gases along with appropriate torch tip.


To avoid thermal shock (cracks) the pre-fired clay dish must be slowly and thoroughly heated, beginning at the very bottom and rotating it so that the dish is heated evenly. Then heat can be applied carefully to the dish sides and rim then directly onto the metal.



The smaller the clay dish is containing the metal or mineral the more heat is transferred to the object to be melted. However, the clay dish/container must be sufficiently large enough to allow for expansion of heated metal/minerals, as well as keep minerals and fluxes from being blown away.





As the silver comes to cool there is a wrinkling of the once smooth molten metal surface. Silver absorbs huge amounts of oxygen when molten and upon cooling it will give up this oxygen, often violently erupting from the molten core to the semi-solid surface. This effect is called sprouting and resembles cauliflower.

Some assayers claim sprouting is a sign of purity, but some old assaying books claim just the opposite, while other old books claim impurities like Platinum will delete sprouting.



A button of metal that originated from a clay dish fusion is placed upon the bottom of a new bone-ash cupel. Just below the metal button I have carved out a small hole to contain the metal in the molten state.

Bone-ash cupels come in 3 standard sizes. The 1.5” wide cupel can absorb about 25 to 30 grams of Lead and cost about1.00 each. The 1.75” and 2” diameter cupels cost about 2.00 each. Depending upon the circumstances I often use all three sizes.


Prior to melting the button the cupel has been slowly preheated around the entire circumference with propane torch so that there will be fewer tendencies to cause thermal shock, which manifests as almost invisible cracks. Cracks can render a cupel worthless, so avoiding this situation due to hasty and uneven heating is really important.

The oxidizing portion of the torch flame is directed just below the rim of the cupel, so that only minor amounts of heated air passes over the metal button. The objective is to keep the area of where the button resides red hot, so that the molten metal(s) will be absorbed into the cupel. Some Lead and other base metals along with tiny amounts of Silver will be oxidized from the surface of metal button and blown away in the hot air current. This becomes quite noticeable by the colored oxides forming on the cupel’s surface near the metal being heated.

Too rapid of heating the metal button can or will cause the molten metal to jump around and usually spit-out tiny pieces of molten metal. This circumstance can be avoided by slow heating and waving the torch flame left and right of the metal, but still mostly on the cupel.

A 1 gram lead button will usually take at least 15 minutes to be thoroughly absorbed into the cupel and hopefully leaving a shiny sphere of silver or gold. A 15 gram lead button may take a couple hours to finish. Sometimes, I have found that a large Lead button become difficult to complete in one spot on the cupel. So, I stop the process and let the metal button come to complete cool. Then I transfer it to another prepared cupel and finish the cupellation. Many old assaying books claim that stopping a cupellation causes lose of precious metals. This maybe true, but I have found that whatever the losses they are negligible and are not a worrisome concern.



As the heat continues there is gradual absorption of the base metals into the boneash and some metal is oxidized by the slight draft over the metal as indicated by the gradual sublimation of hot oxides. These hot sublimation colors are often valuable clues to what the impurities may be.


By directing the concentrated heat left and right a larger portion of the cupel remains adequately heated to absorb the molten lead litharge.


Slowly, the amount of molten metal diminishes as it is absorbed into the bone ash. The red area around the molten button shows that the cupel is absorbing this molten metal. There will also be seen a little smoke rising from the molten button, which is normal and desirable.


Unfortunately, I could not capture a good image of the rolling effect this molten metal creates as it is being absorbed. By barely allowing heated air to pass over the molten metal there forms a rainbow of colors that appear to roll across the surface towards the bottom of the cavity. Sometimes it resembles an oil skim on water.


There are observable phenomena by cupelling in this manner that cannot be witnessed in the electric oven or muffle furnace.


Remaining in bottom of this cavity is a small silvery looking bead.

Just prior to all the lead being absorbed into the cupel, often the Ag prill/bead will get dull then instantly turn very bright. This moment is referred to as a blick, which occurs as the last of the lead leaves the silver. Iit is important to remember that usually some Lead and/or Bismuth can or will remain within the silver prill. To combat this unfavorable circumstance I will remove the silver bead and place it in another tiny hole on another piece of bone-ash , slowly reheat and melt the bead. And, by carefully directing a rather intense flame directly upon the prill there will be seen sublimate color(s) placed upon the cupel surface. If brownish then usually there Lead or Bismuth are gone, but if a yellow color forms then one or both Lead and Bismuth still remain. Unfortunately, by doing this procedure some silver is inadvertently volatilized and lost, but is a small price to pay for being reasonably sure that most undesirable contaminates are gone.

From here I go to the microscope to examine the cupel cavity for effects difficult or impossible for the eye to see, as well as view the surface of the silver prill, which can be informative as to whether or not any of the PGM’s are present.

Remember to keep all clean portions of cupels, which can be used again and again, thereby reducing cupellation expenses.

Often if much bone ash remains I will crush it up and save the uncontaminated portions, which I may use for furnace floor coverings. The point is why not re-claim that which is salvageable?


Based upon all of my previous self-taught experiences relating to utilizing the torch assay procedure I recommend that the learning curve be initiated with melting a piece of lead in a small clay dish and then break the dish, clean the button and then proceed to cupel it.
Because most lead contains some silver, why not see what can be recovered during this phase of learning? After accomplishing this minor feat, move-on to reducing litharge to molten Lead. Add a small piece of silver to the Lead button to see how easy it is to get back what was put in. Doing this simple task will save a lot of aggravation and have the added bonus of allowing accomplishment instead of frustrations.

This next image shows Red Lead oxide (Pb3O4) in a clay dish. This Lead is mixed with layers of powdered whole wheat, which becomes carbon as it burns allowing for some of this Lead oxide to convert to metal.



As heat is gently applied tiny spheres of Lead form where the flour, air and flame meet.


Very gentle heat is all that is required as the wheat burns. Too much heat and the tiny beads of Lead will oxidize into white or yellow PbO. The next image shows how the layering has become visible.

A necessary component of this assaying procedure is a wind break, which allows the torch flame to not be bandied about with gusts of wind. The wind break can be made out of just about anything from plywood to a large diameter chimney stove pipe. The wind break should also be tall enough to vent the smoke away, thereby avoiding breathing the fumes.


Tiny beads of Lead metal are visible clinging to the underside of the red hot Lead oxide and partially burnt flour.


When everything is thoroughly burnt the small molten beads can be mixed together with a knife point, large nail or carbon rod. Then, with more heat the mass of small spheres will become a single button.

As more heat is applied there will usually be formed small beads of metal on the interior side walls, which when the clay is hot enough will run down and collect with the molten button in bottom of dish.



Break the clay dish to retrieve the lead button and remove as much slag as possible.

Place the Lead button in a cupel and begin practicing, By conducting these testing procedure proficiency will be gained making actual mineral fusions easier and with less troubles.


If a microscope is unavailable, use a jeweler’s (prospectors) 10x loupe to examine results.

Often I would use this simple magnifying tool to finish cupellations because the silver prills were so small that it was really hard to know when the Lead was gone from the silver.

Be innovative. Who knows, a simpler way to accomplish this seemingly difficult task might be found.