Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Carnelian

Chalcedony (SiO2) with Iron Oxide inclusions

Druzy Quartz on Chalcedony Matrix

Silicon Dioxide (SiO2)

Quartz (Druzy)

Silicon Dioxide (SiO2)

Weathered iron-rich sandstone or ironstone nodule

Ferruginous sandstone; primarily quartz (SiO₂) cemented or stained by iron oxides/hydroxides such as hematite and goethite

Citrine

Crystalline Quartz (SiO2) with iron impurities

Smoky Quartz and Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich iron oxide aggregate, commonly approximated as FeO(OH)·nH₂O

Likely weathered quartz-bearing rock fragment

Provisional identification: quartz-rich sandstone or microcrystalline quartz (SiO₂)

Concrete fragment with Aggregate

Anthropogenic Concrete with Calcarious and Siliceous Aggregate

Chert / Flint

Cryptocrystalline Quartz (SiO2)

Stromatolite

Biogenic Sedimentary Rock (composed predominantly of CaCO3)

Druzy Quartz

Silicon Dioxide (SiO2)

Druzy Quartz on Matrix

Silicon Dioxide (SiO2) on host rock

Quartz

Silicon Dioxide (SiO₂)

Granite retaining-wall blocks

Granite, principally quartz, potassium feldspar, plagioclase, and mica

Quartz-rich crystalline rock, likely drusy quartz on matrix

Quartz (SiO₂), possibly intergrown with calcite or feldspar matrix

Fossil Coral

Hexagonaria (Rugose coral) / Rugosa

Quartz geode/drusy quartz

Quartz, silicon dioxide (SiO₂), likely chalcedony-lined geode

Ocean Jasper

Silicon Dioxide (SiO2)

Sandstone (Banded)

Arenite (primarily SiO2)

Drupa or Druzy Quartz on Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Iron-stained weathered rock, likely sandstone or ironstone

Ferruginous sandstone/ironstone; mainly quartz (SiO₂) with iron oxides such as hematite and goethite

Brecciated Jasper

Silicon dioxide (SiO2) microcrystalline quartz breccia

Brecciated stone pebble

Breccia

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

Chert (specifically Flint)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silica / Silicon Dioxide), SiO2

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Greenish quartz (likely prase/chalcedony)

Quartz, SiO₂; possibly green chalcedony or chlorite-included quartz

Septarian Nodule Segment (Turtle Stone)

Septarian Concretion (CaCO3 with Siderite or Calcite infill)

Iron-rich sandstone or limonite/goethite concretion

Ferruginous sandstone with limonite–goethite (hydrated iron oxides), possibly a weathered ironstone concretion

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Chert Concretion with Iron Oxide Staining

Microcrystalline Quartz (SiO2)

Sandstone (specifically Flagstone)

Arenite (primarily composed of SiO2)

Basalt with Quartz/Calcite Vein

Aphanitic Mafic Volcanic Rock with Quartz (SiO2) or Calcite (CaCO3) Vein

Quartz Druzy on Geode Fragment

Silicon Dioxide (SiO2)

Quartz Druzy (Geode Fragment)

Silicon Dioxide (SiO2)

Tumbled Black Stone

Unknown, possibly Obsidian, Onyx, or Tourmaline

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone

Clastic Sedimentary Rock

Sandstone

Sedimentary Clastic Rock

Amethyst Geode Fragment

Amethyst (Silicon Dioxide, SiO2) with Quartz matrix