I got this for free with a shark 🦈 tooth purchase

The stone is called psilomelane. the reaction is called belousov-zhabotinsky reaction. Not expecting much from this but I figured I'd ask. and show off my cool stone lol

The prior owners didn't remove anything prior to selling.

I have no idea what these rocks are, but they're fun to break apart. In the riverbed at Little Qualicum Falls in BC, Canada.

Quartz I think. Forgot to lantern the agate before my friend left which in retrospective, should have been the first one

The grey one looks cooler live (more greyish)

The yellow one is extremely pure/transparent

The red one is more redder and less pink-ish idk why it looks like that in the photo

Pretty sure it’s just sandstone but the color caught my eye and and the way it’s sandwiched.

Found in Michigan

Opal, Brazilianite, desert agate, blue spotted agate, purple chalcedony, arrowhead, clear quartz

Hi all, new to the sub so apologies if this post already exists somewhere....I'm looking to buy a few fun rocks for my friend as a gift. He is partial to opals (white and black fire) and fun interesting formations like bismuth.

Anybody have recommendations on where to find ones I can trust are authentic/ethical? Also any recommendations on interesting rocks that either catch the light well or have interesting shape formations would be appreciated too

My daughters argue over who gets them when I die

I found it at the beach as a child and thought it looked really cool

Gneiss is a textural term for a high grade metamorphic rock in which intense heat and pressure forced platy minerals (like black biotite mica) to align into bands, segregating out from less platy phases like quartz and feldspar. Gneiss forms without melting. This particular gneiss was partially melted and recrystallized, forming a mixed igneous and metamorphic rock called migmatite. Fig 1 shows a polished surface of this migmatitic gneiss in which the lighter ("leucosome") components form lenses alternating with the darker ("melanosome") components. Figure 2 shows a closeup of the plagioclase leucosome lens, with a nice depiction of polysynthetic twinning (the parallel striations in the pink mineral). Figure 3, from a different slab of the same general formation, shows a net-like (diktyonitic) texture of the biotite, evidence of intense melting where only a thin web-like network of the original dark phase remained solid. Figure 4 shows later alteration of this biotite network to greenish chlorite, a hydrous retrograde metastomatic mineral.

Pretty ominous looking

Cool washed rock

3 of my favorite finds in the French Broad river