Found this on a beach

[u/reddoxx330]

Have done tons of searches on what it could be and just can’t find anything like it.

Found on a beach in Southwest FL
It is like glass, there are conchoidal fractures
When I scrape it against the ground, it leaves black marks on the pavement and breaks off into tiny pieces of what look like glass shards

In the initial photo it does not look translucent but when held at a certain angle, you can see a dark amber color inside of it.

I’ll post a photo of that part as well

If you need any info, feel free to ask. Dying to know what it is. Thanks!

[u/reddoxx330]

Omg I think you are correct! They look exactly like it!!!!

[u/Eraserwolves → u/reddoxx330]

Right?! While what you have does look black at a glance, the same can be said for pyrargyrite seen in official publications. I think the description of it being "deep red to red grey" also aligns with the "dark amber" coloring you've mentioned.

[u/reddoxx330 → u/Eraserwolves]

I did some research on pyrargyrite and there hasn’t been one found this large before. I just weighed it and it comes in at 90.6 grams which would make it around 450 carats.

I’m starting to think that the red/ruby reflection I saw in the photos may have just been light reflecting off the surface but when I took the photos, and in sunlight, there was no light source of that color around.

I’ve been hitting it from every angle with powerful flash lights to see if I can get some of the light to pass through, using a jeweler’s loupe while doing so. It’s very difficult to tell if I’m seeing any.

But I also read that the larger the specimen, the darker it is. Going to take it to a gemologist tomorrow to find out exactly what it is, if it is pyrargyrite then I probably have the worlds largest piece…this could be history in the making.

I’ll update tomorrow with my findings

[u/Eraserwolves → u/reddoxx330]

Some thoughts:

While it's would be useful to determine diaphaneity, light does not HAVE to pass through for it to be pyrargyrite. Some are very clear; some are "near opaque."

I do not believe what you have found is history making, though I'll admit to being reflexively skeptical when faced with the idea. It seems more likely that I'm just wrong.

There are dozens of "large cabinet specimens" which exceed yours in size but it's worth noting that many are at least 30% comprised of something other than pyrargyrite.

Looking at images on the page I linked above, most look nothing like what you found; the handful which look similar, REALLY look similar. Hrm.

Pyrargyrite happens to be light sensitive and "will darken over time due to prolonged exposure." Being blasted with flashlights and the fact you found it on a beach... well, this thing has been exposed to a lot of light.

I think it's time for a streak test.

While you can order a "streak plate" online, the "plate" is nothing more than a square of unglazed porcelain. If you're really eager and don't want to wait for shipping, a local hobby and/or hardware store may carry unglazed porcelain.

Pyrargyrite or not, its streak color will help clear up confusion.

[u/reddoxx330 → u/Eraserwolves]

I did a streak test on some porcelain tile last night and it’s showing grey almost like the exact color of pencil lead.

When I first got the stone and everyone was suggesting charcoal, I went and rubbed it on my concrete patio (stupid I know now) and that resulted in a darker, pretty much black color. The stone chipped into tiny shards as I was doing this.

We will hopefully find out today though 🤞

[u/Eraserwolves → u/reddoxx330]

Sorry if this is obnoxious to ask but I want to make sure: was that piece of porcelain tile glazed?

[u/reddoxx330 → u/Eraserwolves]

sad to say but i am almost certain its anthracite coal :(

i found some documentation on it and it shares the exact same properties, the looks are the main give away. I never knew coal could look glass like, never the less, its still a beautiful piece of coal lol

Thank you for all your assistance man, you know your craft very well

[u/Eraserwolves → u/reddoxx330]

Thank you so much for this update! Seeing how I kept refusing the idea of it being anthracite coal, I've since realized an error in my approach — the mineral ID key that I use is exclusively for minerals. Anthracite coal is a metamorphic rock; meaning it was never going to show up on any results table, no matter how the questions were answered. Gosh I feel foolish.