Not A Rock

Agate

Agate (Cryptocrystalline Variety of Quartz, SiO2)

Lava Rock (Scoria)

Scoria (highly vesicular basaltic rock)

Basalt River Rock

Basalt (Aphanitic Mafic Igneous Rock)

Yellow Quartzite (River Pebble)

Quartzite (primarily SiO2)

Chert (Siliceous Mudstone variant)

Microcrystalline quartz (SiO2)

André's Landing Rock (Sandstone Boulder)

Newark Supergroup Sandstone (likely Stockton Formation)

Auriferous Quartz (Gold-bearing Quartz)

Silicon Dioxide (SiO2) with Elemental Gold (Au)

Emerald In Matrix

Beryl (Be3Al2Si6O18) with trace Chromium/Vanadium

Carnelian Agate

Chalcedony (SiO2 with iron oxide impurities)

Pyrite in Shale

Iron Disulfide (FeS2) in Argillaceous Shale

Porphyry

Porphyritic Basalt or Porphyritic Andesite

Chert / Flint Nodules in Limestone

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Chert (and Flint variant)

Microcrystalline Quartz (SiO2)

Chert (often called Flint or Jasper)

Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)

Amygdaloidal Basalt with Zeolite/Quartz Infill

Amygdaloidal Basalt (Host: (Mg,Fe)2SiO4 / CaAl2Si2O8; Infill: SiO2 or Na2Al2Si3O10·2H2O)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) with iron oxide inclusions

Gossan (Iron Hat)

Limonitic Gossan (predominantly FeO(OH)·nH2O)

Chevron Amethyst

Silicon Dioxide (SiO2) with iron impurities

Granite Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Oolitic Chert

Silicon Dioxide (SiO2) with oolitic texture

Emerald in Matrix (Quartz/Schist)

Beryl (Be₃Al₂Si₆O₁₈) with Chromium/Vanadium impurities

Sandstone (specifically an Iron-Concretion)

Arenite with Iron Oxide (Limonite/Goethite) cementation

Milky Quartz

Silicon Dioxide (SiO2)

Chert (Flint/Jasper variety)

Microcrystalline Quartz (SiO2)

Agate (Moss or Dendritic Agate)

Chalcedony (Silicon Dioxide, SiO2)

Quartz (specifically Milky/Gray Quartz)

Silicon Dioxide (SiO2)

Sandstone Concretion

Clastic Sedimentary Rock (primarily SiO2 with mineral cement)

Milky Quartz with Matrix

Quartz (Silicon Dioxide, SiO2)

Sandstone with Quartz Veining

Arenite with hydrothermal quartz (SiO2)

Quartz (Water-worn pebble)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily composed of SiO2)

Quartzite

Quartzite (primarily SiO2)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Biotite Mica

Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)

Bronzite

MgSiO3 (Enstatite with 10-30% FeSiO3 in solid solution)

Sandstone

Arenite (primarily SiO2)

Granodiorite

Granodiorite (Intermediate intrusive igneous rock)

Smoky Quartz

Silicon Dioxide (SiO2)

Blue Apatite

Apatite group (Ca5(PO4)3(F,Cl,OH))

Blue Sapphire (Tumbled/Polished)

Corundum (Al2O3)

Sodalite

Sodalite [Na8(Al6Si6O24)Cl2]

Sandstone (Ferruginous)

Arenite (Fe2O3 enriched)