Sedimentary Or Igneous Fragment

Conglomerate

Sedimentary Conglomerate

Iron-stained limestone or coral fragment

Calcite-rich carbonate rock; chiefly CaCO₃ (exact identification is uncertain from the image)

Worked chert (likely flint)

Microcrystalline quartz/chalcedony, SiO₂

Red jasper / iron-rich chert

Microcrystalline quartz (SiO₂) colored by hematite/goethite

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃)

Milky quartz fragment

Quartz (silicon dioxide, SiO₂)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Orthoclase Feldspar

Potassium aluminum silicate (KAlSi3O8)

Breccia

Clastic Breccia

Pyrite

Iron Disulfide (FeS2)

Likely vertebra fossil or bone fragment

Indeterminate fossilized vertebra; mineralized hydroxyapatite, commonly Ca₅(PO₄)₃(OH)

Chert (specifically Tan/Yellow Chert)

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Calcite (likely chalky calcite fragment)

Calcite, calcium carbonate (CaCO₃)

Given the appearance, it's likely a fragment of an igneous or metamorphic rock composed of multiple minerals. Without specific diagnostic features, it's difficult to give a common name other than 'crystalline rock fragment'. If pressed to guess based on the granular, somewhat light and dark speckled appearance, it could be a fragment of granite or a related intrusive igneous rock.

As a rock fragment, it does not have a single scientific mineral name; rather, it's a piece of a rock which is a combination of minerals. If it were granite, its main mineral composition would be quartz (SiO2), feldspar (e.g., KAlSi3O8 - orthoclase, (Na,Ca)(Al,Si)4O8 - plagioclase), and mica (e.g., KAl2(AlSi3O10)(OH)2 - muscovite or K(Mg,Fe)3AlSi3O10(OH)2 - biotite), among others.

Fossilized Bone Fragment

Vertebrate Fossil

Greenstone

Metamorphosed Mafic Igneous Rock

Obsidian (likely black volcanic glass)

Obsidian; naturally occurring rhyolitic glass, primarily SiO₂

Weathered mafic rock (probable basalt or gabbro fragment)

Basalt–gabbroic rock; chiefly plagioclase feldspar and pyroxene, possibly olivine

Obsidian (likely snowflake or smoky obsidian fragment)

Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Glacial Cobble with Granite Inclusion

Porphyritic Basalt or Andesite containing Granitic Xenolith

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon dioxide (SiO2) within a nodule

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Calcite crystal

Calcite (calcium carbonate, CaCO₃)

Quartz (Crystal Fragment)

Silicon Dioxide (SiO2)

Citrine Geode Fragment

Citrine (Silicon Dioxide with Iron Impurities), SiO2

Metallic sulfide mineral specimen, likely pyrite

Pyrite (FeS₂), possibly a pyrite-rich sulfide aggregate

Polymict conglomerate with a projecting pebble

Conglomerate; clast-supported polymict conglomerate, dominated by quartz/feldspar and lithic fragments in a cemented matrix

Weathered sandstone or iron-rich mudstone fragment

Clastic sedimentary rock, likely quartz–feldspar sandstone with iron-oxide cement

Chert (and Agate/Quartz in Geode-like Nodule)

Silicon Dioxide (SiO2)

Chert (Flint Arrowhead)

Microcrystalline Quartz (SiO2)

Chert (Arrowhead/Tool Grade)

Microcrystalline Quartz (SiO2)

Weathered fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Sandstone (Ferruginous)

Arenite with Iron Oxide (Limonite/Hematite) coating

Banded Sandstone (Water-worn Pebble)

Arenite with mineral banding