So far all i can say is most likely it is a fracture point making a rift or subduction material likely all the same one. My neighborhood on one end lake Grubb on the other. So maybe just wasn’t hot enough to make Dimond but got over that 1720°
melting point . Or maybe it is just quartzite. I know I have Tridymite
I should stay out of this but do agree that the appearance of the rock looks like botryoidal hematite. I have some specimens from Iron Mountain SD with a peacock iridescent sheen that look just like the photos… the rock is notably heavy just by picking it up in a hand specimens as befits it’s SpG… furthermore, hydration of the hematite will cause it to turn limonitic, with the brown ferric iron mineral goethite which accounts for the brown coating on the specimen…that being said, looks can still be very deceiving. Hematite perse is very weakly magnetic… at room temperature it’s antiferromagnetic becoming paramagnetic at a high temperature…it will not be attracted to a magnet unless magnetite is co-present.
So far as this being black tourmaline is concerned, absolutely NOT. Schorl tourmaline crystallizes into hexagonal prisms as bespeaks it’s hexagonal crystal system (trigonal)… is found in pegmatites and coarse grained granites derived from S type granitoids or from melts from derived from ultra metamorphic felsic rocks. Boron, LILE, Uranium, and other incompatibles are concentrated in these melts and magmatic fluids…Shorl has a white streak, hematite typically red… pushing too hard against the streak plate can give you a misread, especially with soft materials, because it could pulverize the material leading to a misleading (!) streak color. I do not believe that tektites or meteorite material is relevant to the photo… tektites are a glass, derived from earthly crustal material… rocky meteorites are mafic and often cannot be distinguished from an aphyric basalt by visual inspection…someone mentioned obsidian… obsidian is a glass of rhyolitic silica composition…obsidian does not form “grapes” or botryoidal structures… if there’s any structure to it, it will be flow banding as it derives from quickly chilled rhyolitic lava. Like all glasses, the fracture is conchoidal. So far as chalcedony is concerned, it won’t feel heavy in the hand as would hematite… it, like all quartz stones will streak white…
I could be over generalizing but these are some of the basic properties of these minerals and glasses.
Nobody needs to be a geologist by profession to find out for themselves what fits the best for their mineral specimen… all of the world’s knowledge is at the tips of your fingers on the internet… you just have to know what questions to ask… the more questions you ask of the internet, the greater your knowledge base will be… (“I hold in my hand a device that contains all of the knowledge of the world.
instead I use it mostly for looking up pictures of cats and hurling insults at strangers”… Cartoon from the New Yorker about a man with a smartphone)…
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I had found the id on this one i beleve its goethite
goethite will be the brown material on the outside of your specimen if your black shiny rock is hematite…
It’s what is known as bog or swamp iron ie a mixture of botyroidal hematite coated with limonite and goethite. It forms from magnetite by martitization to hematite and then further decomposition to hydrated iron oxides. The hematite is normally non-magnetic unless there is some residual magnetite left.
i definitely know that I have several large chunks of it… iron mountain is the type locale for botryoidal hematite from Custer county SD… Limonite per se is not one specific mineral but a mixture of hydrated ferric iron oxides. Its stoichiometric formula is ferric oxyhydroxide… Fe00H…other polymorphs of ferric oxyhydroxide are present including Feroxyhyte and lepidocrocite… the lepidocrocite is what I believe is coloring the samples iridescencent peacock colors on the surface… I left the big pieces out in the yard and the colors faded with time with sun and rain exposure. Iron mountain is capped by a layer of it… it actually attracts lightning strikes being on a mountain top. Not a usual place for bog iron. but hematite/limonite residuals can form in other ways as in gossans… bog iron itself forms from the partial reduction of ferric iron bearing solutions to partly ferrous by decaying organic material in an anoxic acidic environment. hence the magnetite…reoxidation on the surface in oxygen rich water creates bog iron… agglutination of the ferric and minimal ferrous iron and their microcrystallization lead to its formation in bog settings.
Just on the basis of pictures alone I would consider botryoidal hematite… further testing is still need to confirm…you can almost tell that it’s an oxide of iron, just by the weight in your hand… it’s quite heavy and beyond anything that is silicate.
If anyone has an extra 10/15 million dollars sitting around doing nothing…please buy a laser ablation mass spect, an electron microprobe, and a Raman spectrometer… laser ablation masspect is particularly good… it’s gotten so sensitive that it can count and weigh individual atoms, separating them by isotopes…it’s also only minimally destructive, as a very small aliquot of surface material can be lasered off and run…in an emerald crystal, it will give the Cr, Fe, V content… other trace elements can locate the mine or provenance where it came from, in addition to giving the paraenesis…I’ll run it or you…LOL!!!
Yeahthats the plan but like i said IM DISABLED AND SSDI is not a enough to pay for my medical care let alone to afford these tools HENSE MY PROBLEM
I don’t have that kind of money either… hense is spelled, hence by the way…,
I agree it’s not a Tektite. I don’t think it’s meteoritic at all.