In Roughing It, Mark Twain wrote:
"The Sagacious reader will know now, without being told, that the speculative miner, in getting a "fire assay" made of a piece of rock from his mine (to help him sell the same), was not in the habit of picking out the least valuable fragment of rock on his dump pile, but quite the contrary. I have seen men hunt over a pile of nearly worthless quartz for an hour, and at last find a little piece as large as a filbert, which was rich in gold and silverand this was reserved for a fire assay! Of course the fire assay would demonstrate that a ton of such rock would yield hundreds of dollarsand on such assays many an utterly worthless mine was sold."
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The Scientific Method and Reliable, Unambiguous Data:
How to Avoid being Duped!
Scams generally involve attempts to convince someone that a rock is enriched in gold and/or other precious metals when it is not. Using principles of the scientific method, we can confirm or discount this assertion in an unambiguous, accurate, and reliable way. Let's look at a probably familiar analogy to review how the scientific method works and why we have come to trust its results.
We are probably all most familiar with medical studies that make use of the scientific method. We have probably all heard (more than once) about blind studies in which one experimental group is administered a new medicine while another group is not. The researchers are looking for differences between the two groups that are unambiguously attributable to the treatment. So the scientists have gone through the mental exercise of hypothesizing that a medicine will cause an effect in patients and then designing an experiment to demonstrate conclusively that the medicine does or does not cause the anticipated effect. Because some results may be psychosomatic, the group not receiving the treatment is not told that they are the control group and may be given a placebo (for instance a pill that looks like the real medicine but is not). This is called a blind study. However, because the treated group may respond psychosomatically because they know they are being treated with the experimental medicine, they may not be told so either in what is referred to as a double-blind study. These scientists are going to great lengths to be certain that the effects that they see or measure between the two groups are the result of the treatment alone. They are using the scientific method to ensure the accuracy and reliability of their results and thereby avoid misinterpreting the results of their experiment because of unforseen effects or by studying one variable when some other variable or variables are actually producing the measured results.
In a similar way, in establishing whether or not a rock contains gold, we must take steps to ensure that the results of our assay accurately reflect only the presence or absence of gold. We generally do three things during the analysis. First, we carry a blank through the entire analysis, treating it as though it were a sample by adding to it all of the chemicals that we add to the real sample in the course of the assay. In this way, we would measure any small amount of gold that we might inadvertently add to the sample because we would also add it to the blank as we add the chemicals to them both. Ideally we want to measure zero gold in the blank, indicating that we have been very clean in our analysis. If we do measure a small amount of gold in the blank, we subtract that same amount of gold from the unknown sample result, thereby carefully monitoring this contamination and correcting for it.
Secondly, we carry a standard along through the analysis. This is a natural sample, similar to the unknown, in which we already know the gold content with high confidence. At the end of our analysis, after treating the standard like just another unknown sample, we expect to find the certified amount of gold in the standard, indicating that our assaying method was an accurate one (precious metal standards are available from the Nevada Bureau of Mines and Geology as described inside the front cover). And finally, we analyze more than one replicate of a sample, carefully assessing the variation in results between the duplicate or triplicate determinations of gold in a given sample to ensure that we can repeat our results time after time and getting a measure of how precise our analysis is. After having taken these precautions during our analysis we have high confidence that we know the concentration of gold in the unknown sample. We have monitored the analysis for inadvertent contamination by including a blank, we have verified the accuracy of the analysis by including a standard (or even several different standards), and we have demonstrated the reproducibility of our method. We can further assure ourselves that we have the proper answer by conducting the analysis by two or more entirely different methods. All methods should give similar results.
Final Advice
Before investing money in any mining-related endeavor, seek advice from a knowledgeable friend or hire a consultant to help you assess the risks inherent in the venture. Spending a little money on a consultant in the beginning may save a lot of money in the long run.
If you are having material assayed, take it to a reputable laboratory (make some telephone calls to mining companies, state geological surveys, the Better Business Bureau, etc.). If you think that you have found samples that contain ore-grade concentrations of precious metals, have them re-assayed at a second commercial laboratory to confirm the results; a significant investment may hinge on these numbers. If the two laboratories do not agree within some reasonable margin of error, after you have provided them with identical, carefully split samples, seek a third, fourth, etc., until you are satisfied that you know what the concentrations are with high confidence (samples can be submitted for assay to the Nevada Bureau of Mines and Geology, see inside the front cover).
While many are attracted to mining because of the potential to obtain riches from rocks, prospecting or investing in mining is an expensive and risky venture. It is often said that if it sounds too good to be true, it probably is. But in this business, there are indeed some valuable ore deposits left to be discovered, so proceed with great care and assistance, if necessary. Be systematic, apply liberal doses of common sense, and control your "gold fever."
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Some Classic Indications of Scams
Although exceptions could occur, the following are typically indications of a scam rather than a legitimate orebody. Be cautious if you hear any one of these:
"You must use a proprietary or nonstandard technique to assay the ore."
(Standard analytical techniques unquestionably detect ore-grade precious metals in all geological materials, such as rocks, soils, or water. Fire assay, neutron activation, inductively coupled plasma-mass spectrometry, and atomic absorption spectrophotometry are standard techniques that, when properly performed, yield accurate assays of gold in ores.)
"There are not only gold and silver but also platinum group elements in the ore."
(Most ores do not have substantial quantities of both platinum and gold. Other platinum group elements, including ruthenium, rhodium, palladium, osmium, and iridium, rarely occur in economically significant quantities in gold deposits.)
"This deposit is so large that it will upset the world market when it is mined."
(Most legitimate large discoveries are bought by major mining companies, not peddled to individual investors.)
"Nearly all samples analyzed have ore-grade concentrations."
(Most ore deposits have pockets or zones of unprofitable waste rock.)
"The ore occurs in rocks, sediments or other materials that rarely, if ever, contain ore in other places in the world."
(We know of no significant precious metal deposits in what appear to be unaltered cinder cones, unaltered lava flows, playa sediment, brine, or groundwater.)
"The ore is substantially higher grade than most ores."
(It is rare to find substantial tonnages of ore, say more than a few thousand tons, containing more than $300 worth of precious metal per ton.)
"All the samples taken during exploration were sent to the assay laboratory."
(Prudent exploration geologists will save splits of the samples from drilling, trenching, and examining old underground workings to check the assays and to further investigate where the precious metals occur in the rocks.)
"Reserves of over a million ounces of gold have been discovered, but few, if any, exploration holes have been drilled into the deposit."
(The term "reserve" has legal meaning with the U.S. Securities and Exchange Commission and should only be applied when there is a high degree of confidence that the stated grade and tonnage of the ore and the total recoverable quantity of gold are known. Generally hundreds of exploration holes are drilled and thousands of samples are assayed before being able to define a reserve of a million ounces of gold.)
If it sounds too good to be true, it probably is.
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Conversion Factors
1 part per billion (ppb) = 1 nanogram per gram
1 part per million (ppm) = 1 microgram per gram = 1 gram per metric ton = 1000 ppb
1 metric ton = 1000 kg = 2205 pounds avoirdupois
1 ounce per ton (troy ounce per short ton avoirdupois) = 34.286 ppm
1 troy ounce = 31.10 grams = 0.06857 pounds avoirdupois
1 pound = 16 ounces avoirdupois = 14.583 troy ounces = 453.59 grams
1 assay ton = 29.167 grams
NBMG Standards
A number of precious metal standards, useful for validating results from commercial laboratories, are available from NBMG. These include gold, silver, and platinum-group element standards in several rock-types and concentrations. Call for prices and availability.
Assaying Services at NBMG
The Nevada Bureau of Mines and Geology provides assaying services to Nevada residents and prospectors. Samples can be submitted for the analysis of gold, silver, platinum-group elements, and other constituents if the sample is from Nevada and the individual is a resident of Nevada. Price lists are available from the Publications Sales Office or the Geochemical Laboratory on request. Several reputable commercial laboratories operate in Nevada and elsewhere.
Continuing Education at the University of Nevada, Reno
The Nevada Bureau of Mines and Geology periodically conducts a two-day fire assaying shortcourse through the Department of Continuing Education athe University of Nevada, Reno. Call (702) 784-6691 for details.
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