Organic (Often Found By Beachcombers)

Chert (specifically a fragment with Desert Varnish)

Microcrystalline quartz (SiO2)

Chert (Smooth River Pebble)

Silicon Dioxide (SiO2)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Silica (SiO2)

Fossilized Megalodon Tooth Fragment

Otodus megalodon (Carcharocles megalodon fossil)

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Glauconitic Sandstone (Greensand)

Glauconitic Sandstone ((K, Na)(Fe3+, Al, Mg)2(Si, Al)4O10(OH)2)

Chert (Chocolate or Brown Flint)

Chert (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Jasper/Iron-stained Quartzite)

Silicon Dioxide (SiO2)

Blue Agate (Tumbled and Dyed)

Silicon Dioxide (SiO2) with likely organic dyes

Chert (Chert / Flint)

Silicon dioxide (SiO2) - Microcrystalline quartz

Petrified Wood

Silicified Wood (SiO2)

Chert (River Pebble)

Microcrystalline silica (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Gray Chalcedony)

Microcrystalline Quartz (SiO2)

Glauconitic Sandstone (or Greensand)

Glauconitic Siliciclastic Rock (Containing (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Pearl

Calcium carbonate (CaCO3) + organic conchiolin (Biogenic Mineral)

Pearl

Calcium Carbonate (CaCO3) with Conchiolin

Chert (often called Flint)

Chert (Microcrystalline Quartz, SiO2)

Crushed Limestone

Calcite-rich Sedimentary Rock (CaCO3)

Jasper (Green/Yellow Moss Jasper)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (River Cobble)

Chert (Cryptocrystalline Quartz, SiO2)

Chert Nodule (Flint)

Microcrystalline Quartz (SiO2)

Chert (Green variety)

Microcrystalline Opaline/Quartz (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Jasper variation)

Chert (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (Iron-stained)

Silicon Dioxide (SiO2)

Chert (Brown variety / Common Jasper)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (principally Silicon Dioxide, SiO2)

Chert (often called Flint or Jasper)

Cryptocrystalline quartz (SiO2)

Fossil Coral (Rugose Coral Fragment)

Rugosa (extinct order of solitary and colonial corals)

Chert (Chert Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (Nodule)

Chert (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (specifically Gray/Blue Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Brown Jasper / Chert Pebbles

Microcrystalline Quartz (SiO2) with iron oxide impurities

Ferruginous Sandstone (Ironstone)

Arenite with Iron-Oxide Cement (FeO(OH)·nH2O / Fe2O3)

Petrified Wood

Silicified Wood (SiO2 permineralization)