Help Identifying Potential Platinum Nugget

[Dringle1122]

From what I can tell, relative density, mohs tests and visual similarities from other samples across the internet all point to a platinum nugget. Found it beachcombing along the PNW.

[F350Platinum]

6 hours ago, Dringle1122 said:

From what I can tell, relative density, mohs tests and visual similarities from other samples across the internet all point to a platinum nugget. Found it beachcombing along the PNW.

It will have to displace more water than gold and feel heavier.

Here's a couple pictures of platinum nuggets:

This one is from Russia:

This is from California:

Lucky find if it is. 👍

[Steve Herschbach]

Could be. Seems a hair too light colored though that can vary. Weight would tell if it is aluminum or not. Platinum is also very hard, if it is soft, it's not platinum. If heavy and hard, a real solid might be. If it was mine I'd hit it with a propane torch and see if it melted, as platinum has a very high melting point, but I'm not suggesting you do that. As a precious metal it is also resistant to acid. So heat and acid tests are part of the equation.

It's the beachcombing part that worries me. People don't find platinum nuggets beachcombing, so it raises the possibility it is metal that has been melted in a fire, then worn by beach action to look like a natural nugget.

[GB_Amateur]

3 hours ago, F350Platinum said:

It will have to displace more water than gold....

Displacement of water is a measurement of volume.  Density is mass (or weight) divided by volume.  So for two equal weights the more dense one will displace less water.  I assume this latter point is what you were getting at, but you got it reversed.  Happens to me all the time.  😉

 

[F350Platinum]

17 minutes ago, GB_Amateur said:

Displacement of water is a measurement of volume.  Density is mass (or weight) divided by volume.  So for two equal weights the more dense one will displace less water.  I assume this latter point is what you were getting at, but you got it reversed.  Happens to me all the time.  😉

 

Thanks GB. 🤣 Appreciate the correction. 👍

[Joe D.]

Welcome to the forum Dringle!

   I don't know where PNW is, but here on the beaches of the Space Coast, we get different kinds of melted looking blobs, besides aluminum, from exploded rockets! But both Steve and F350 have set you on the right path! You can also take it to a jeweler to identify for you, if your not confident in you testing abilities! You don't have anything for scale, so it's hard to judge size! Good luck in your identification, and I hope it is platinum!!👍👍

[mcjtom]

There is 'the Archimedes trick' to try to estimate the density of your nugget a little more tightly - for the size like this you would need a scale with resolution of 0.01 g to narrow the range (less than that probably won't cut it - it will give you large range of possible densities so it will be hard to identify the metal by it).

1. Weigh the dry nugget
2. Put a cup of water on the scale, zero the scale
3. Dip your nugget in water but suspended from a thread or a thin wire
4. Note the scale reading (it will be negative, but essentially its absolute magnitude is equivalent to mL of displaced water and thus measures the volume of your nugget.
5. Divide the dry nugget mass (in grams) by the nugget volume (in milliliters or cubic centimeters) to get its density and see how close it is to platinum or other metals and their alloys that you suspect.

Interpretation may be a bit more complicated because there is an uncertainty and range of values involved (hence the need for high-resolution scale to get the volume tightly enough), but I made a little calculator that simplifies things (it may not look like it at first but I promise that it does 🙂

https://docs.google.com/spreadsheets/d/1Srt7cy0Fx_xkNjQO7IVXo-aK01jEYygS_W0VQZAbTCQ/edit?rm=minimal#gid=0

You can change the values in white cells - the rest is calculated.

[jasong]

I would say not platinum - based on what appears to be a whitish oxidation occuring. I don't think platinum oxidizes white, think it's more brown to black. Lead will oxidize white though (think of the coating on an old dug up bullet), as will a number of other more common metals that are harder than lead. 

The good old density trick described above will tell the difference between lead and platinum. The key is doing it accurately though, as a lot of people who try are not very careful and it only takes a little inaccuracy to skew the result.

[GB_Amateur]

39 minutes ago, mcjtom said:

Note the scale reading (it will be negative...

Pretty sure it's positive.

40 minutes ago, mcjtom said:

Interpretation may be a bit more complicated because there is an uncertainty and range of values involved (hence the need for high-resolution scale to get the volume tightly enough)

19 minutes ago, jasong said:

The key is doing it accurately though, as a lot of people who try are not very careful and it only takes a little inaccuracy to skew the result.

Yes, and yes.  The precision (effectively the smallest weight the scale with read) in combination with the actual weight of the specimen are very important.  Most people use a scale with too large of a precision for the object they are trying to determine the density of.  0.01 g and even 0.001 g precision are often needed for determining densities of small items just to get within 10% accuracy.

Another source of error is the volume of the immersed string/wire/thread.  That can typically be corrected for -- subtracted a calculated volume a couple different ways.  (One is direct -- from length and diameter, the other indirect -- by weight and known density.)  Bubbles on the immersed specimen?  Moisture on the dry specimen?  Those, too.

Elemental metals (i.e. pure forms such as gold, silver, lead) as well as alloys can be all over the place in terms of density.  But a simple division is low, medium, high.  Low (say under 6 g/cm^3) include aluminum and magnesium.  High (over 15 g/cm^3) include gold, most of the platinum group metals (PGM's), and tungsten.  Middle (7.5 g/cm^3 to ~12 g/cm^3) are the often found iron (and steel), copper (and brass, bronze, pewter alloys), zinc, silver, and yes, lead.  Differentiating between these groups is typically a lot easier than differentiating within a single group.  E.g. Silver vs. lead?  Visual clues (depending upon patina) might differentiate but using densities, even with the pure forms, takes careful measurement technique.

The last source of (qualitative) error in these kinds of discussions is claiming that 'feel' can determine density.  'Feel' might give an indication of weight.  Then you use your eyes to estimate volume.  Then....  Even the "guess your weight" carnival worker would have a difficult time accurately estimating density of the things we find detecting.

[F350Platinum]

Whatta ya bet this person doesn't come back? Hope so, but... 😀