Rock (Likely Sedimentary)

Granite

Phaneritic plutonic rock (composed primarily of Quartz, Feldspar, and Mica)

Polished red gemstone pendant, likely red jasper or brecciated jasper

Jasper: microcrystalline quartz (SiO₂), commonly with hematite or iron-oxide inclusions

Brecciated jasper, possibly rainforest jasper or brecciated rhyolite

Brecciated microcrystalline quartz (SiO₂), commonly called jasper; the green portions may contain epidote, chlorite, or iron-bearing silicates, while red-brown areas are typically hematite or other iron oxides

Porphyritic Andesite

Andesite (Porphyritic texture)

Basalt with Alteration Crust

Basalt (SiO2 range 45-52%)

Quartz (likely Clear Quartz or Rock Crystal)

Quartz (SiO2)

Limestone with Chert Nodule

Carbonate rock (CaCO3) with Microcrystalline Silicon Dioxide (SiO2) inclusion

Quartz Vein in Host Rock (Likely Slate or Shale)

Hydrothermal Quartz (SiO2) in Pelitic host rock

Green glass-like cabochon, likely synthetic glass or resin

Unidentified green transparent material; possibly molded glass, synthetic spinel, or resin

Granite

Granite (a felsic intrusive igneous rock)

Biotite-bearing granite or granitic gneiss

Quartz–feldspar–mica rock; chiefly quartz (SiO₂), feldspars, and biotite mica

Gneiss (specifically a granitic gneiss cobble)

Gneiss (high-grade regional metamorphic rock)

Basalt with Quartz Infill

Basalt (Mafic Extrusive Volcanic Rock)

Coarse Sand or Fine Gravel

Clastic Sediment (unconsolidated)

Fossiliferous Limestone

Fossiliferous Limestone (CaCO3)

Granite Cobble

Granite (Phaneritic Igneous Rock)

Likely iron-rich rock or metallic mineral fragment

Uncertain; possibly limonite/goethite-rich material or weathered iron meteorite fragment

Mixed rock and mineral collection

Mixed lithologies; likely quartz, feldspar, basalt, granite, chert, sandstone, and metamorphic rocks

Porphyritic Basalt (or Andesite) containing Augite

Porphyritic Mafic Volcanic Rock

Basalt Pebble

Basaltic Igneous Rock

Quartz (likely tumbled or naturally water-worn)

Quartz (SiO₂ - Silicon Dioxide)

Vesicular basalt (likely weathered volcanic rock)

Basalt, commonly composed of plagioclase, pyroxene, and olivine

Tumbled pale stone, likely milky quartz or calcite

Quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

Quartz-rich granitic rock, possibly pegmatite

Granite/pegmatitic granite; chiefly quartz (SiO₂), feldspar, and mica

Quartz Pebble (Tumbled / Beach Pebble)

Silicon Dioxide (SiO2)

Banded Iron Formation

Banded Iron Formation (BIF)

Milky quartz-rich vein rock

Quartz, SiO₂, likely massive or microcrystalline quartz

Mixed Mineral Collection

Multi-mineral Assemblage (Quartz, Jasper, Obsidian, Pyrite, etc.)

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Brick fragment (Man-made material)

N/A (Fired clay)

Polished orbicular jasper / brecciated jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and clay-rich inclusions

Diorite with Xenolith

Intermediate Plutonic Igneous Rock (Diorite)

Dark coarse-grained rock, likely basalt or gabbro

Basalt (fine-grained) or gabbro (coarse-grained), composed mainly of plagioclase feldspar and pyroxene

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Tumbled yellow jasper (likely serpentine or calcite-rich stone)

Jasper: microcrystalline quartz (SiO₂); exact yellow veining may indicate serpentine, calcite, or iron oxides

Glacial Erratic (Sandstone/Quartzite)

Glacial Erratic specimen (likely Orthoquartzite or Feldspathic Sandstone)

Weathered quartz-rich rock, likely milky quartz/quartzite

Quartz (SiO₂), possibly quartzite with minor iron-oxide staining

Polished rhyolite (likely porphyritic rhyolite)

Rhyolite, composed chiefly of quartz and alkali feldspar with minor plagioclase, biotite, and iron oxides

Unidentified dark pebble

Undetermined; possibly polished basalt, chert, or iron-rich stone

Mica-bearing quartz rock (likely pegmatite)

Quartz–feldspar–mica pegmatite; dark mica is probably biotite, possibly muscovite or chlorite

Not a rock, mineral, or geological specimen

Quartz-rich metallic sulfide ore (probable pyrite-bearing rock)

Pyrite, FeS₂, in a quartz-rich host; exact identification is uncertain from the image