# formula for ppm to troy oz.



## loco

I had lost alot of info in notes I had on a laptop that was stolen. Can someone post for information on converting ppm to grams or troy oz. from an assay. I had an assay pulled on some material and I got the ppm reults just can't remember how to roughly figure out the material. thanks so much.

-Rich


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## loco

ok sorry I guess maybe I didn't give enough information. for arguement sake lets say I have 1,000 lbs of material, and I have the ppm assay results how can I estimate the metal value of the material.


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## Noxx

1 ppm mean 1 part per million or 0.0001%

Let say your material has 500ppm of gold, you have:

500 x 0.0001% = 0.05% gold


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## loco

ok found these by seraching as well. Are these accurate??

1 ppm = 1 gram
1 gram = .03215 troy oz
31.1034768 grams = 1 troy oz

I know the latter 2 are correct but am not sure if the above mentioned 1ppm = 1 gram is accurate.


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## Oz

PPM is a concentration value, not a mass value.


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## loco

thanks Oz that's what I was thinking but I googled it and there was a site claiming that to 1 ppm = 1 gram.

by the way I am dealing with converter material here, if that helps. thanks again guys.

- Rich


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## Oz

It does not mater what the material is but if you have 1 million grams of converter material then 1 PPM = 1 gram. Does it make sense that way?


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## Irons

Oz said:


> It does not mater what the material is but if you have 1 million grams of converter material then 1 PPM = 1 gram. Does it make sense that way?



1 PPM = 1 milligram per Kilogram= 1 gram per Metric Ton (2200 Lbs)


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## Oz

I was trying to make the illustrative point of what PPM is but it is far more useful as Irons put it as most times you will find PPM the rest of the data will be metric. Just in case there is a question, there is indeed 1 million grams in a metric ton.

I have always appreciated the simplicity of the metric system, except when having to convert it to or from other systems. The nice thing to remember is that the gram is the same the world around.

Thanks for putting it into a more useful format Irons.


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## Irons

Oz said:


> I was trying to make the illustrative point of what PPM is but it is far more useful as Irons put it as most times you will find PPM the rest of the data will be metric. Just in case there is a question, there is indeed 1 million grams in a metric ton.
> 
> I have always appreciated the simplicity of the metric system, except when having to convert it to or from other systems. The nice thing to remember is that the gram is the same the world around.
> 
> Thanks for putting it into a more useful format Irons.



You're quite welcome. Now if we can only get the troglodyte peckerwoods. to quit referring to the Metric system as a communist plot designed to bring down our way of life.


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## Oz

That is too funny! The only beneficiary I see to the multiplicity of measuring systems we have would be the tool manufacturers. For mechanical work I need 3 sets of tools, Standard, Metric, and British Whitworth. 

Since masses are often quoted in cubic centimeters it might be useful to some to know that 1 cubic centimeter is equal to one milliliter, both measurements of volume. That can be very nice in determining the volume of irregular materials and comparing it to known masses of elements or alloys based in cubic centimeters. I would think most here own a beaker or a more accurate graduated cylinder


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## goldsilverpro

I use traditional U.S. (the last bastion) and like it for certain things. I also use metric for some things and troy for some things. All three can be handy. Among these, I probably have at least 100 conversions memorized. In our business, all are used and all should be learned in order to prevent confusion.



> 1 cubic centimeter is equal to one milliliter



And, of course, they both contain very close to one gram of water.


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## macturney

The answer to your question is: enter the ppm number in your calculator and divide by 34.286 and that will be the weight in troy ounces.
MacT


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## g_axelsson

macturney said:


> The answer to your question is: enter the ppm number in your calculator and divide by 34.286 and that will be the weight in troy ounces.
> MacT


Easy answer and wrong. The question was wrong at the start, like asking how many square foot there are per meter. Notice that I didn't say square meter.

Whatever your sample weight is, divide it by a million and multiply it by the ppm value. ppm means parts per million.

For example 7 ppm of 3400 ounces. That would be (3400/1000000)*7 = 0.0034*7=0.0238 ounces.

If you have a ton of ore then a ppm is a gram. If you have a million ounces of ore then a ppm is one ounce.

And on that note... can someone from the other side of the Atlantic explain how much a yard is when talking about mining, it drives me crazy to hear the people talking about yards when discussing how much material they run through the wash plant. Is it cubic yards or something else?

You must be crazy to continue using measurements based on the body size of some ancient English king. Come join the rest of the world using the communistic system developed by the French revolutionaries during the French revolution in 1799. It's about time.... :lol: 

Going back to your answer I would say that you need to look up the difference between avoirdupois and troy ounce. precious metals are measured in troy ounces... unless you use metric, then it's easy.

What you say? You measure volume in ounces too... I'm outta here. :wink: 

Göran


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## snoman701

Lol...a yard is 3 feet (36 inches) just short of a meter. 


Sent from my iPhone using Tapatalk


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## g_axelsson

snoman701 said:


> Lol...a yard is 3 feet (36 inches) just short of a meter.


That was what I was thinking, but they run 300 yards per hour through a washplant in Goldrush Alaska...

Göran


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## snoman701

Yeah....it's a lot of dirt. A yard is a lot of dirt when all you've got is a shovel!!!




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## goldsilverpro

I use all sorts of units in calculations but, for thinking purposes, I prefer units that I can visualize. I can visualize an inch but not a centimeter - unless I think of a cm as ~0.4 inches. A mile but not a km - unless I think of a km as ~0.6 miles. A pound but not a kg - unless I think of it as ~2.2 pounds. Visualizing a mm is totally out of the question unless I put it in terms of it being 1/25.4 part of an inch - between 1/32" and 1/16" (both of which I can visualize). It's impossible for me to think in terms of meters. The only metric units that I have fully adapted to and like better are the liquid measurements of 3.7849 liters or less. Anything greater, it's a tossup as to whether I use gallons or liters. However, if I had a figure of 138 liters, I would always divide it by 4 and approximate the gallons when doing it in my head. I'm not real big on working with quarts and I always think of a fluid ounce as being almost 30ml. And, of course, a ton is 2000 avoirdupois pounds. It contains 29,166 troy ozs. One thousand kg, or ~ 2204 pounds, isn't a ton in my book. It's a metric ton. It contains 32,150 troy oz.

A yard (actually, it's a cubic yard) is 27 ft3. I can visualize a yard - it's a cube that comes up to my navel (I'm 5Ft-9in = 175cm tall). A ft3 will contain 7.5 gallons. A ft3 is one and a half 5 gallon buckets.

And then there's a cup, a tablespoon, a teaspoon, a pinch, a tad, a smidgen, a dash, and a passel.

The original question, asked 8 years ago, makes no sense. Ppm is a measure of concentration. Troy ounce is a measure of weight or mass. Apples and oranges.


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## g_axelsson

Are you talking about short or long tons? :mrgreen: 

What feels good is what we are used to.

A meter is the length between my shoulder and the tip of my other hand, perfect for counting meters of cable when installing equipment, 10 kilos is what I can hold with my arm straight out.
A dm is a tenth of a meter, a cubic dm is the same as a liter or a 1/1000 of a cubic meter. A ml is a 1/1000 of a liter, making a ppm of a cubic meter a cubic cm. A cubic meter of water is a ton and a ppm of a ton is a gram.
There is 1000 meters in a kilometer, there is a 1000 grams in a kilogram, a ton should really be called a megagram but that's a small quirk. Then we have micrometer that is 1/1000 000 of a meter, nanometer is 1/1000 000 000 of a meter, picometer is smaller than an atom (atoms are in the size of 100 pm or Ångström... named after a very small Swede  ).

So if there is 10 mg per kilo how much is it per ton... 10 g per ton. No need for long calculations, it is easily done by shifting the decimal or changing the prefix.
People working with electronics is used to the different prefixes, pico (10-12), nano (10-9), micro (10-6), milli (10-3), kilo (103), mega (106), giga (109)
Other than that I can't think of any conversions I need to memorize.

Oh... yes, water freezes at zero degrees and boils at 100. That is something most people have experienced. Making freeze mixtures by mixing ice and salt not as commonly. 

Metric is even easier to spell than ardivoipuo... ardovipou... pounds and ounces. :mrgreen: 

Göran


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## snoman701

goldsilverpro said:


> I use all sorts of units in calculations but, for thinking purposes, I prefer units that I can visualize. I can visualize an inch but not a centimeter - unless I think of a cm as ~0.4 inches. A mile but not a km - unless I think of a km as ~0.6 miles. A pound but not a kg - unless I think of it as ~2.2 pounds. Visualizing a mm is totally out of the question unless I put it in terms of it being 1/25.4 part of an inch - between 1/32" and 1/16" (both of which I can visualize). It's impossible for me to think in terms of meters. The only metric units that I have fully adapted to and like better are the liquid measurements of 3.7849 liters or less. Anything greater, it's a tossup as to whether I use gallons or liters. I'm not real big on quarts and I always think of a fluid ounce as being almost 30ml. And, of course, a ton is 2000 avoirdupois pounds. It contains 29,166 troy ozs. One thousand kg, or ~ 2204 pounds, isn't a ton in my book. It's a metric ton. It contains 32,150 troy oz.
> 
> A yard (actually, it's a cubic yard) is 27 ft3. I can visualize a yard - it's a cube that comes up to my navel (I'm 5Ft-9in = 175cm tall). A ft3 will contain 7.5 gallons. A ft3 is one and a half 5 gallon buckets.
> 
> And then there's a cup, a tablespoon, a teaspoon, a pinch, a tad, a smidgen, a dash, and a passel.
> 
> The original question, asked 8 years ago, makes no sense. Ppm is a measure of concentration. Troy ounce is a measure of weight or mass. Apples and oranges.



That's really funny, and it goes to show our education, and the change over the last, what? 40 years? I can picture everything, gram, mm, cm, m, km, ml, 6ml, 12ml 20ml 35ml 60ml then it goes 355 ml then 1L, but then I'm done...can't do kg, . But i can't picture a liquid ounce (after thinking about it, a shot glass)...1 lb, can do. I remember cm, mL etc from learning units. There was a plastic cube in school, 1 mL, 10 mL, 100 mL & 1L...it had cubes & rectangular shapes that were to scale that nested all together. Inches offer no such easity. Who can remember how many cubic inches there are in a gallon, or in a liquid ounce....and then pound, at least it's traditionally written in decimal. Might as well use stones.


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## goldsilverpro

Goran,
In 50 years, I can't specifically remember using the "long ton" in a calculation, although I probably have. I've always known it was 2240 pounds. I never knew how it was derived until I just now looked it up. It's one of those goofy British things involving 14 pound "stones". Here's the Wikipedia definition:

"A long ton is defined as exactly 2,240 pounds. The long ton arises from the traditional British measurement system: A long ton is 20 cwt, each of which is 8 stone (1 stone = 14 pounds). Thus a long ton is 20 × 8 × 14 lb = 2,240 lb,"

How a cwt, a hundredweight, comes out as 112 pounds is beyond me. Washington and Adams surely knew about "stones" but, thank God, stones have been completely eliminated from our (U.S.) memory over the last 200 years. When most people here say ton, they mean 2000 pounds. period.

The one unit I hate above all others is dm, decimeter. First of all, the meter, itself, is a BS unit. It is, "equal to one ten-millionth of the distance from the equator to the pole measured on a meridian:" Give me a break. Does anyone care about that other than the guy that proposed it? What was wrong with the yard? I spent 10 years as a PM plating guru and one of the most important relationships in plating was that of ASF, "amps per square foot", the amount of amperage you must apply per square foot of surface area on the part being plated in order to get decent plating. Unfortunately, the plating industry has gone metric and, instead of ASF, it is now amps/dm2. I could visualize ASF, but not this amps/dm2 idiocy. I can't wrap my brain around it. Of course, I am 77 and am an analog type of guy.

Snoman,
For 50 years, I've known that there are 231 in3 in a gallon. I use this factor more often than you would think.


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## g_axelsson

I just learned about the hundredweight (but my spellchecker knew more than me...) and the definition of a ton in imperial before I wrote my first post on this thread. That is how I just learned there is a long and a short ton.

When the meter was first devised it was at an age when every country had it's own standard or even more than one. Since it has it's roots in the French revolution they didn't have a king to use as the standard. I agree, the definition of the meter could be anything as long as everyone agrees on it. Today it is based on how far light travels in vacuum in 1/299 792 458 seconds, just because we can measure that with a very high degree of precision.
The metric system replaced a forest of different measurements systems back in the days.

Fun fact, the Swedish government tried to introduce a decimal system based on feet and inches, so for a while there were ten Swedish inches in a Swedish foot. The only trace left of that system is a Swedish mile ("mil" in Swedish) that is ten km. So instead of saying there is 56 km to my parents I'm saying there is 6 mil to drive. At least it's still decimal. A mil was slightly longer when it was first defined and it was based on a suitable distance between inns.  
https://en.wikipedia.org/wiki/Swedish_units_of_measurement

Sweden went metric in 1889 but it took more than a hundred years until planks were sold in mm instead of inches ("tum" in Swedish). It takes several generations until a change like this goes through. Today there is only three countries that hasn't officially adapted the metric system, USA, Myanmar and Liberia.

But it's fine with me, you can go on and use imperial if you like. I only need the conversion factors from imperial to metric and then I do my calculations there.  

Just to rub things in... the definition of the yard is based on the meter since 1959. :lol: 

Göran


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## Geo

In the US, gold is weighed in the pennyweight and grains, not grams. Of course the refinery will give both units on the assay printout. If you want to talk about antiquated measurements, lets talk about furlongs, a rod, a hector, a peck, a bushel, a stone.


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## 4metals

Real confusion enters the picture when you talk about tons. In the US a ton, also called a short ton or a US ton, is 2000 pounds. Where a metric ton is 2204 pounds or 1000 kg. When I talk about ppm as a measure of gold content I assume (and assumptions can be dangerous) that we are speaking about a metric ton because 1 ppm equals 1 gram per metric ton. The confusion comes from mixing ton types and thinking the PPM logic follows, it does follow but staying in metric makes it easy and clean. 

And although I have lived with our system of weights and measures here in the US all my life, I much prefer science done metrically.


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## snoman701

I have my tape measures quantified in barley corns personally.

Units was the first month of high school chemistry class. Learning to move between them, learning them, learning the importance of them.

Science, always metric, as you said. 

The weird part is machining, always english. But engineering, it depends on WHAT you are engineering. I still do all structural engineering calculations in english, while mechanical engineering is done in metric.


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## geedigity

Don't forget the difference between weight and mass. Here in the states we say pounds. Is it pounds force or pounds mass. Elsewhere it is either gram (mass) or newtons (force).  If I use a balance, I am measuring pounds mass. If a digital scale or spring loaded one is used, I believe will not measure mass but measure weight or pounds force.

When our scale reports the amount of something to us, in grams for example, that may not actually be the truth. What type of scale are you using? When you think about it, your scale should report the result correctly i.e. Newtons not grams (unless the scale is a balance) or pounds force/pounds mass. 

Sounds like a bunch of hogwash, but this will probably become important to me when I get into mining asteroids or other places with a different gravitational accelerations. At that time a gram in space will have to be a gram here on earth. 

However, it is very unlikely I will get the opportunity to mine asteroids in my lifetime and therefore, I guess it doesn't really matter what type of scale you use to measure weight or mass.


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## g_axelsson

geedigity said:


> Don't forget the difference between weight and mass. Here in the states we say pounds. Is it pounds force or pounds mass. Elsewhere it is either gram (mass) or newtons (force). If I use a balance, I am measuring pounds mass. If a digital scale or spring loaded one is used, I believe will not measure mass but measure weight or pounds force.
> 
> When our scale reports the amount of something to us, in grams for example, that may not actually be the truth. What type of scale are you using? When you think about it, your scale should report the result correctly i.e. Newtons not grams (unless the scale is a balance) or pounds force/pounds mass.
> 
> Sounds like a bunch of hogwash, but this will probably become important to me when I get into mining asteroids or other places with a different gravitational accelerations. At that time a gram in space will have to be a gram here on earth.
> 
> However, it is very unlikely I will get the opportunity to mine asteroids in my lifetime and therefore, I guess it doesn't really matter what type of scale you use to measure weight or mass.


You are right in that a scale usually measures the force and just assume that the gravity is a constant. For most times that gives enough precision. When needing higher precision we use a calibration weight to adjust for any local variations. Equator or near the poles, high up in the mountains or down at sea level, living on top of a massive iron ore, all would affect a high precision scale.

A common scale that isn't affected by local gravitational variations is, as you say, a balance where you match the masses on two sides of a precision balance, but that won't work in zero gravity. Another way to measure mass is by using a spring and measure oscillations, that measures inertia that is directly proportional to mass. So when going for mining those meteorites, don't forget your springs and stopwatch.  

Personally I prefer that a scale is calibrated in mass rather than force... It can be fooled by pressing down on it with a finger, but that's okay. If it was reporting force then it would still be true even if you push down on it but then you would have to know the local gravity constant and calculate the mass from force divided by g.

To bring this back to where we started... anyone else know why the formula given by macturney is wrong? Not just that the original question was wrong?

Btw, I highly suspect he was a drive by spammer that will come back in a week and edit his post to include a spam link. He spent 8 minutes on the forum and made a comment on an old thread. The reason I suspect him being a spammer also relates to the paragraph above.

Göran, physicist on retainer. :mrgreen:


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## 4metals

The best guess I can get as to what he was posting about in with his factor was an assay ton, which he got wrong. In dealing with a metric ton an assayer uses a sample weighing 32.666 grams which makes every milligram in his sample equal to one ounce of gold in the ore. (edit, in a Metric Ton of the ore, to be clear!)

Or if using a US Ton, it's 29.1666. (Just to add to the confusion) 

If he really meant 34.286 maybe he was part of that generation that studied the "new math"!!!!


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## goldsilverpro

Short ton: https://www.google.com/search?q=troy+ounces+in+a+short+ton&ie=utf-8&oe=utf-8

Metric ton: https://www.google.com/search?q=troy+ounces+in+a+metric+ton&ie=utf-8&oe=utf-8

Long ton: https://www.google.com/search?q=troy+ounces+in+a+long+ton&ie=utf-8&oe=utf-8


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## 4metals

> For 50 years, I've known that there are 231 in3 in a gallon. I use this factor more often than you would think.



Funny you should mention that factor Chris, I probably use it multiple times every week for some of the strangest things. 

For example, I just built a new raised bed for planting in the greenhouse, the wife said she would bring 5 gallon pails from our topsoil pile to fill it. My first thought is she won't last long! So I did the trusty 96 x 30 x 24 = 69,120/231 = 299 gallons / 5 = 60 trips to the pile. That number changed her mind, I had to carry them all! 

Maybe it's not such a handy factor, if I didn't use it I might have gotten 4 or 5 loads out of her before she quit. Oh well, it is handy sometimes.


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## US minetrash

Goran and 4metal had a good laugh (in their superior, knowing way) at macturney regarding his conversion factor, but mac is CORRECT.
And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?) at a grade of 7 ppm??? I can tell him that a 7 ppm ASSAY will not equate to a grade of .0238 oz/ton (troy).

Mac was talking about getting an assay returned to him in ppm, or parts per million. This refers to a concentration without units.
And remember, over here it's troy ounces per avoirdupois ton

Mixing units is easy to do, but you're going to get confused if you do. A 7 ppm assay (here in the states) is not the same as 7 grams per tonne (I'm NOT talking about metric tons), but even so, it's a GOOD assay. And 7/34.286 IS about .2 oz/ton...high grade where I come from. Even a 7 gram per metric ton assay will NOT equate to about .028 opt.

Where does that 34.285 number come from? Let's try 480 grains of gold (a troy ounce) in a ton, meaning 2000 lbs, each of 16 oz, each ounce of 437.5 grains ( a troy oz is bigger than a av oz). 2000X16X437.5= 14 million grains. 480/14 million is .000034286, the concentration factor for 1 tr oz/ton. You can also see that you can multiply your ppm Au assay by .02916 to get the same #. 7 ppm X .02916= .204 oz/ton troy.

Over here we're used to drilling results in feet ( a lot of 5-foot intervals) and assays in oz/ton. It works.


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## g_axelsson

US minetrash said:


> Goran and 4metal had a good laugh (in their superior, knowing way) at macturney regarding his conversion factor, but mac is CORRECT.
> And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?) at a grade of 7 ppm??? I can tell him that a 7 ppm ASSAY will not equate to a grade of .0238 oz/ton (troy).
> 
> Mac was talking about getting an assay returned to him in ppm, or parts per million. This refers to a concentration without units.
> And remember, over here it's troy ounces per avoirdupois ton
> 
> Mixing units is easy to do, but you're going to get confused if you do. A 7 ppm assay (here in the states) is not the same as 7 grams per tonne (I'm NOT talking about metric tons), but even so, it's a GOOD assay. And 7/34.286 IS about .2 oz/ton...high grade where I come from. Even a 7 gram per metric ton assay will NOT equate to about .028 opt.
> 
> Where does that 34.285 number come from? Let's try 480 grains of gold (a troy ounce) in a ton, meaning 2000 lbs, each of 16 oz, each ounce of 437.5 grains ( a troy oz is bigger than a av oz). 2000X16X437.5= 14 million grains. 480/14 million is .000034286, the concentration factor for 1 tr oz/ton. You can also see that you can multiply your ppm Au assay by .02916 to get the same #. 7 ppm X .02916= .204 oz/ton troy.
> 
> Over here we're used to drilling results in feet ( a lot of 5-foot intervals) and assays in oz/ton. It works.





macturney said:


> The answer to your question is: enter the ppm number in your calculator and divide by 34.286 and that will be the weight in troy ounces.
> MacT


Macturney never said per ton. That was my main point I tried to get through. And I wasn't alone.


Oz said:


> PPM is a concentration value, not a mass value.



And the original question was about ore, but the next line he specified it by


loco said:


> ok sorry I guess maybe I didn't give enough information. for arguement sake lets say I have 1,000 lbs of material, and I have the ppm assay results how can I estimate the metal value of the material.



Given that question you can't just give a conversion factor without specify which weight it is related to. The correct answer with 1000 lbs is not 0.0342857139 but half, 0.01714285695

ppm simply means part per million and has no unit in itself. ppm is a scale factor of exactly 1/1000000.

I have no problem with calculate ppm to troy oz/ton... 1 ton (2000 lbs) = 7000*2000 grains = 14 million grains.
Then 7 ppm per ton is equal to 7/1000000*14000000 = 7*14 =98 grains per ton.

With 480 grains per troy ounce there are 14000000/480=29166.667 troy ounces per ton.
Then 7 ppm per ton is equal to 7/1000000*29166.667 =0.20417 troy ounces per ton.

Checking... 480*0.20417 = 98.0016 grains
1000000/29166.667 = 34.2857139 and the dimension is
million /(troy ounces/ton) = how many millionth of a ton (avoirdupois) there is in one troy ounce.

Ref : 
https://en.wikipedia.org/wiki/Avoirdupois
https://en.wikipedia.org/wiki/Troy_weight

Finally...


US minetrash said:


> And check out Goran's reply...WTH does 7 ppm of 3400 ounces mean?? 3400 oz (what unit?)


7 ppm of 3400 ounces is 0.0238 ounces (unit ounces, fl oz, toz, oz... pick one)
7 ppm of 3400 grams is 0.0238 grams
7 ppm of 3400 goats is 0.0238 goats
7ppm of 3400 is 0.0238, we don't need any units at all if we don't want it.
ppm doesn't affect what unit we uses, it is just a number and exactly 1/1000000.

If people learns to use math then they wouldn't have to memorize so many conversion factors.

Göran


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## goldsilverpro

Goran said:


> If people learns to use math then they wouldn't have to memorize so many conversion factors.


I can do both but, since I understand all the math involved, the factors I memorize are much more meaningful and more permanently built into my head. I've saved a lot of time in my life by memorizing factors. To me, it's always been quite important to do so.


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