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m&h

metallurgy

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Yesterday we found a mark about three miles northwest of Sisters, Oregon. We were struck by its unique (to us, anyway) appearance. It is a standard disk from the Bureau of Public Roads under the U. S. Department of Agriculture, set in 1926, and last reported on in 1943. Despite this apparently peaceful existence, the metal of the disk has the deep shine of gold, rather than the soft gray-green oxidation of brass or bronze. On the edge where the word “BUREAU” appears, there was an overgrowth of hardened moss, which we removed with a blade, but we gave the disk no further cleaning of any kind.

 

There is no evidence that the disk has recently been used professionally. Its vertical location is "posted," so its usefulness is probably limited.

 

We always hit snags when we try to put links or photos in our posts, but we’ve logged the mark, QD1020.

 

Does anybody have a notion what this disk is made of?

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m&h--Yeah, aren't those pretty? I hope someone here has an answer about what they're made of.

 

There are a bunch of BPR pipe caps in Yosemite, set in the 1920s and '30s. In fact, I use one as the first waypoint for my Stories in the Rocks geocache. I've had people ask me whether the mark is really the original one or has been replaced recently. As far as I know, it's the original one. It still looks just as bright and shiny as you described.

 

BTW, someone tipped me off recently that you can display photos in forum postings by uploading them to the avatar section of your Groundspeak account. You don't have to actually turn them into avatars! They're just stored there, and you can see the URL and use it here.

 

Patty

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This is the one we found in Zion National Park.

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HO0158 H 22 The year it was monumented was 1928.

 

And so you know that it seems to be the years between 1920 though 1930 rather than it being in National Parks or National Areas, here are two out in the boonies of Mohave County, AZ.

 

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FS0434 2557 The year it was monumented was 1920.

 

and

 

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FR0677 2879 The year it was monumented was 1920.

 

(Edited to add 2 other disks.)

Edited by 2oldfarts (the rockhounders)

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I've got one too. I was wondering about the color when I saw it. It's from 1923:

 

JW0886

 

47f2215c-17e6-4ff1-8cdc-b98583f1a75b.jpg

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I've been involved in assisting in some maintenance on large boats (50+ feet) which had beautiful clean bronze screws (propellers). They looked to be about the same color of those marks. Looks like a type of bronze to me. There are many different alloys (mixtures) of metals that can be called bronze, primarily "copper alloys, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon.", to quote Wiki on the subject. Seems like it could be bronze to me. Some alloys will darken or change appearance, depending on environmental conditions, but some ("better ones") will not. I'm not a metalurgist, just a chemical engineer. I started looking for my reference books, but they're buried pretty deep..... [sure as heck not gold!! Wish it was, but we'd probably find a lot fewer markers....].

Edited by Klemmer & TeddyBearMama

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Here's another goldie - Spruce.

5958_100.jpg

 

A related old topic discussed green versus brown disks.

 

I'd tend to guess that these gold ones are a bit more likely brass than bronze, but in either case, they show a metallic color for some reason, rather than an oxidation color.

 

It's possible that these gold colored disks neither brass (Cu+Zn) nor bronze (Cu+Sn), but instead aluminum-bronze, an alloy of copper and aluminum, sometimes used in making gold-colored coins.

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Here are two more. I wonder if they were Bright-Dipped or Anodized? Look how PTS 8 is starting to oxidize in the center where it's damaged.

 

PTS 9

 

faac2497-623e-48fc-b54f-f2e0d3ec6835.jpg

 

PTS 8

 

1cb960e8-7f41-4a47-a5a4-89c4d6775e71.jpg

 

 

Got the Titles mixed up.

Edited by Mega Scooter

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WIKI Brass

 

In the earlier years more of the better alloys were added and made them different colors see above.

 

As the metals became more valuable less was added of the better alloy and more of the lesser alloy was added creating a darker look.

 

Like with the Gold Standard until 1964 if you remember coins had almost all silver in them as time went on more copper (alloy)was added and the coins sound and look different.

Even earlier pennies are a better grade of copper.

 

Just a little of my research and knowledge.

I did take Metalurgy I II III but have forgotten all the alloys and their perspective alloy combinations.

I would have to look it all up again.

 

Forgot to add my Golden Oldie.

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WMY9R B 1923 MO

Edited by GEO*Trailblazer 1

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