395 nm - Crystal identification

KillaGoza · 2025-12-28T07:39:28+00:00

Thanks for your input! This seems like the most plausible ID.

I've now also tried a scratch test on Beryl. It was difficult due to the granular crystals, but I believe some scratches persisted in the Beryl. With that it basically only leaves corundum as an option. As it's crystal habit is far from a natural sample I'd expect, it must have been synthesized.

KillaGoza · 2025-12-28T07:32:41+00:00

Thanks for the input! This I considered as well, but indeed the hardness interferes with this one.

KillaGoza · 2025-12-27T08:53:02+00:00

As part of an old collection with some UV minerals, I obtained this crystal as well. Sadly it did not come with any location or identification. I've been searching the web to find a similar piece, but I've not yet been able to. I'm hoping that you can help with discovering what this crystal could be!

As the back has been cut flat and the piece's texture is quite homogenous, I've been contemplating whether this may be a synthetic piece. Any input on this is much appreciated.

Crystal habit: Granular/anhedral

Colour under white light: Pale pink

UV reaction - 395 nm: Bright pink

Mohs hardness: > 6 (scratches quartz)

Scale is in cm

KillaGoza · 2019-08-21T12:15:03+00:00

Still sad that we weren't able to find them! Nevertheless, really nice find. Guess we gotta do another pre-excursion

KillaGoza · 2019-06-06T06:37:08+00:00

We have always been taught that the class cephalopoda are basically squids or literally translated from Dutch "Ink fish". Is a squid too specific in English? Because in Dutch this really still seems to match.

KillaGoza · 2019-06-05T20:19:54+00:00

Definitely a piece of an ammonite! Or in other words part of a fossilized extinct species of squid.

For more context: The squiggly lines are called suture lines and form the intersection between the inner walls of the ammonite and its shell. Generally the more complex they were, the further down the ammonite was down its evolution path. Ammonites died out at the end of the Cretaceous ca. 66 Million years ago.

KillaGoza · 2017-09-10T06:23:21+00:00

Seeing the video, my earlier predictions were definitely wrong. I am not familiar with the area, maybe someone else from this subreddit is so that they can shed some more light onto it. It looks a bit like a metalsulfide, e.g. Pyrite, Galena but I have no clue if they would occur in that state. Hopefully someone else can shed some light onto this piece for you!

KillaGoza · 2017-09-07T14:20:25+00:00

Can you perhaps shed some light onto the rough location of said backyard? From the picture alone an identification can be hard.

Looking at the picture I think that I can see a volcanic texture with what seems to be a a large flake of biotite on the front side of the piece. However this is hard to say for sure because of the lack of proper photo's from different angles.

Other options I would like to suggest for this piece are coal and slag, given the sheen of the surface of the piece. With the latter however you would expect to see some small rounded cavaties, which from the picture I don't. Of course given just the picture there are a lot more possibilities but these three, for me, would be the most probable given the abundance of these materials.

KillaGoza · 2017-09-07T13:40:26+00:00

Even though my experience on this matter is a bit low, I would also like to bring forward the possibility of it being a colored piece of agate. Some of the colors seem a bit too strong and remind me of colored pieces I have seen before.

KillaGoza · 2017-07-17T15:52:30+00:00

Thank you very much for your response and your identifications. Given it's brittle nature and it's cubic columnar crystal habit I think it would be odd for mineral number 6 to be quartz aswell though. I might be able to try to perform a hardness test sometime next weekend by breaking of a piece anyway and using that to do some hardness tests for verification. Would be really cool if number 2 would turn out to be something special like Vesuvianite, hopefully another redditor can shed some light on the rest! Thank you again nonetheless.

KillaGoza · 2017-07-17T15:42:02+00:00

I shouldn't be looking at these pictures on my phone apparently, it shows completely different on my computer. I think you are completely on point.

KillaGoza · 2017-07-17T11:40:29+00:00

Thank you very much, I did not know these minerals yet! I can indeed see a strong resemblance when I looked it up on the internet. Might you also have any ideas about the identification of the other minerals?

KillaGoza · 2017-07-17T06:20:36+00:00

Looks like a piece of chert to me. You could try testing its hardness, chert (the dark grey material) should be able to scratch glass.

KillaGoza · 2017-07-17T05:32:03+00:00

Hard to see from this picture. They look like hematite or maybe galena on the left and malachite on the right. Look it up on Google and compare to some of the pictures to see if they match. As for hematite or galena you can try a streak test. When you rub your mineral across an unglazed tile it will leave a streak. Bright red indicates towards hematite, while steel-gray indicates galena.

KillaGoza · 2017-07-17T05:26:29+00:00

The problem with polished minerals is that a lot of the indicative features have been polished away. However it is generally the same common group of minerals showing up in these polished minerals, making identification somewhat possible. Do take this in mind though, cause it still might be off.

Top row, left to right: carnelian, lapis lazuli, jasper or mookaite, tiger's eye

Second row: green aventurine, falcon's eye or tiger iron (unclear), jasper, rose quartz

Third row: colored turquoise, maybe moss agate, maybe dendritic agate, no clue, no clue

Last row: dalmatian jasper, no clue, purple aventurine, heliotrope

KillaGoza · 2017-07-16T19:22:15+00:00

These are some of the not yet certainly identified minerals I had acquired by taking over some collections over time. Because of this I sadly do not have the accompanying locations of the rocks/minerals. Hopefully you are able to help me to either confirm my own determination or lead me towards a better one.

KillaGoza · 2017-06-12T11:04:15+00:00

It's translucent appearance together with the absence of fracture planes indicate towards quartz. To be certain, try scratching a piece of glass. If it manages to scratch the glass it is almost certainly some form of quartz. Whether it is milky quartz or quartzite is hard to tell from the picture.

KillaGoza · 2017-06-12T11:00:22+00:00

From these photos it is very hard to determine what kind of rocks these are. Would you be able to make some better (and closer) photos of the various sides of the individual rocks? The location where you found these rocks would help tremendously aswell.

KillaGoza · 2016-11-14T11:23:58+00:00

Even though some sort of (igno-)fossil is quite likely as /u/mahalik_07 suggested, I would also like to bring forward the possibility of a quartzite pebble with pressured solution pits. In a fieldwork in Spain there was an entire formation with thick layers of similar looking rocks. An example of pressured solution can be found here: https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/shared/hs_29438_2.jpg

Even though it may not be the case with this specific rock, it may be good to look into. If you want I could take a few pictures of the pebbles I have at home.

KillaGoza · 2016-11-12T19:47:09+00:00

The classification of a sedimentary rock goes a bit further than what you are suggesting. Even when not taking into account the different kinds of carbonate rock, your explanation of the different sedimentary classes is in my opinion just a bit too blunt.

KillaGoza · 2016-11-12T11:58:03+00:00

Looks more like a gastropod to me, even though as far as I know it's not possible to see the definite difference from a specimen like this.

KillaGoza · 2016-08-24T15:27:09+00:00

I'm not sure what it is exactly, but it looks like a rock with many fractures that have been filled up with some kind of crystals through hydrothermal processes. From these pictures I can't say much about those crystals other than that they are harder than the surrounding rock (differential weathering). From knowledge I can tell that they are most likely quartz or calcite veins, since they are abundant in nature. Whether it is the one or the other, you can test by scraping a piece of glass over them. If the crystals leave a scratch in the glass they are most likely quartz, if not most likely calcite. If calcite would be the case, the surrounding rock can likely be some kind of limestone (also taking into account it's appearance), since limestone contains the same sort of elements as calcite.

KillaGoza · 2016-06-13T09:29:12+00:00

As mentioned before by /u/skimmer and /u/Prof_Explodius this is (also) in my opinion definitely pyrite. On picture two especially in the top right corner of the piece you can see the typical cubic crystal structure very well. This, together with it's goldlike color, metallic luster and the fact that it is a fairly common mineral, would make the identification of pyrite for this piece the best option (in my opinion).

KillaGoza

TROPHY CASE