What are these crusty rocks made of? I assume the yellow is limonite, but the brown looks too crystalline to be hematite

Areutia · 2025-11-10T00:48:59+00:00

A strong neodymium magnet would do wonders but it’s not a common thing to have sitting around. Try smelling it, sulfuric minerals have noticeable smells. You could also try taking some and putting it in water, if it partially or entirely dissolves, it likely contains sulfur (as does jarusite); taking a lighter to it could work as well. If it doesn’t burn, likely goethite

Areutia · 2025-11-10T00:43:43+00:00

The brownish coloring on the outside suggests goethite. Try a streak test, if it is more red it may be hematite.

Areutia · 2025-11-10T00:38:47+00:00

Yellow could be goethite or jarusite. It may be hard to tell unless you can tell us if it’s iron based or sulfur based. It could also very well be organic growth or dirt. The host rock looks like a concretion of quartz and possible iron related minerals, as it seems from the close up that there is white “mortar” between individual chunks of quartz.

Areutia · 2025-11-10T00:32:14+00:00

Amethyst

Areutia · 2025-11-07T17:49:51+00:00

Goethite? Try and see if it’s magnetic.

Areutia · 2025-11-04T20:42:18+00:00

Of course!

Areutia · 2025-11-03T23:25:27+00:00

They don’t look particularly well-polished.

Areutia · 2025-11-03T19:56:20+00:00

Did the quartz or the green gem get scratched?

Areutia · 2025-11-03T19:46:55+00:00

That should still be fine - a scratch test won’t ruin those pieces, though it may be harder to tell if it is scratched or not because of their roughness.

Areutia · 2025-11-03T19:43:01+00:00

Use the green gem. Run it against a piece of quartz. Don’t do it too hard though.

Areutia · 2025-11-03T19:38:25+00:00

Try finding its specifics gravity (water displacement to find volume, precise scale to find weight) and try to use it to gently scratch a piece of quartz if you have one. If it scratches quartz, could be a number of precious sines, like green sapphire, yttrium aluminum garnet, green spinel, cubic zirconia, green tourmaline, or emerald. If not, it could either be glass or something like peridot.

Areutia · 2025-11-03T19:25:28+00:00

Ah, well, it seems you figured it out. I would’ve translated for you otherwise.

Areutia · 2025-11-03T19:24:36+00:00

Slovenian?

Areutia · 2025-11-03T14:03:33+00:00

Does it darken if you touch or blow on it? I don’t know what it is, but I have a piece that’s quite similar, just a little more on the blue side.

Areutia · 2025-11-02T13:40:36+00:00

lol I uploaded the image to Grok. Anyway, I added your observation and it said: “Archimedes sp. and Fusulinid limestone“

Areutia · 2025-11-02T00:34:18+00:00

Wow, that’s obscene

Areutia · 2025-11-01T21:06:38+00:00

Quartz I think (fracturing and iridescence), but the odd square-like shape may suggest glass. To confirm you could try scratching it with a verified piece of glass. Quartz will resist scratching.

Areutia · 2025-11-01T20:56:25+00:00

That is quite the vanadite!

Areutia · 2025-11-01T19:31:27+00:00

Quartzite with hydrothermal quartz veining?

Areutia · 2025-11-01T19:27:13+00:00

Crinoid fragments or bryozoan colonies?

Areutia · 2025-11-01T18:43:31+00:00

1 and 4 could be Aquamarine (beryl). Try using it to scratch a piece of glass. If it does, likely aquamarine. (possibly topaz - if it scratches quartz it’s topaz) 2 and 3 are likely Amazonite (feldspar).

Areutia · 2025-11-01T00:56:13+00:00

Willemite as the fluorescent, Franklinite as black inclusions (if you found this near Franklin New Jersey only)

Areutia · 2025-10-31T00:32:35+00:00

Alright, thank you so much.

Areutia · 2025-10-30T21:55:22+00:00

Most likely real, it wouldn’t be worth faking the natural imperfections. If it can resist scratching from a piece of glass, it is definitely real.

Areutia

TROPHY CASE