Coral limestone / fossil coral
Biogenic calcium carbonate, chiefly aragonite or calcite (CaCO₃); likely fossilized colonial coral
fossil
Category
Man Made Composite (Lithified Equivalent Of Sedimentary)
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Hematite (Iron Ore)
Hematite (Fe2O3)
mineral
Metallic sulfide ore, likely pyrite-bearing rock
Pyrite (FeS₂), possibly with marcasite or other sulfides
mineral
Red Jasper (possibly Brecciated Jasper or Bloodstone variety)
Jasper (Silicon Dioxide, SiO2)
sedimentary
River Rock (Granitic Gneiss)
Foliated Granitic Gneiss
metamorphic
Sandstone
Arenite (Sedimentary rock composed of sand-sized grains)
sedimentary
Sandstone Concretion
Clastic Sedimentary Rock - Quartz Arenite / Sandstone
sedimentary
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions), SiO2
sedimentary
Conglomerate
Conglomerate
sedimentary
Pearl (Biogenic Mineraloid)
Calcium carbonate (CaCO3) primarily as Aragonite
mineral
Carnelian Agate
Silicon Dioxide (SiO₂), a variety of Chalcedony
mineral
Chert (with Chalky Cortex)
Silicon Dioxide (SiO2)
sedimentary
Cockle Shell (Fossil or Recent)
Class Bivalvia, Family Cardiidae (e.g., Cerastoderma edule for common cockle)
Sedimentary (Biogenic, a type of fossil)
Red Sandstone
Arenite (SiO2 with Fe2O3)
sedimentary
Banded sandstone pebble
Quartz-rich sandstone, likely with a contrasting siltstone or fine-grained sandstone band
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Tumbled jasper, likely red/brown jasper
Microcrystalline quartz (chalcedony), SiO₂, colored chiefly by iron oxides
mineral
Blue calcite (probable)
Calcite, CaCO₃
mineral
Conglomerate (Puddingstone)
Conglomerate (specifically, clastic sedimentary rock)
Sedimentary
Banded Sandstone
Clastic Sandstone (SiO2 with iron oxides)
sedimentary
Chert (Nodule)
Silicon dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Chert / Flint Nodule
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Red Jasper
Jasper (Silicon Dioxide with iron oxide inclusions), SiO2
mineral
Ferruginous Quartz (Red Jasper/Carnelian Agate)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
mineral
Gneiss pebble
Banded gneiss, commonly quartz–feldspar–biotite gneiss
metamorphic
Chert (Flint)
Chert (microcrystalline quartz)
sedimentary
Carnelian Agate
Silicon Dioxide (SiO2) - variety of Chalcedony
mineral
Concretion
Various mineral compositions, typically carbonate or iron oxide cemented sediment
Sedimentary
Red Jasper (with Quartz inclusions)
Silicon Dioxide (SiO2)
sedimentary (physico-chemical)
Chert (or Flint)
Silicon dioxide (SiO2)
sedimentary
Chert Pebble (Jasperoid/Flint)
Silicon Dioxide (SiO2) - cryptocrystalline quartz
Sedimentary
Aragonite Star Cluster (or Aragonite Sputnik)
Aragonite (Orthorhombic Calcium Carbonate, CaCO3)
mineral
Diamond (Cut Gemstone)
Carbon (C)
gemstone
Chalcedony (Common Opal/Chert variety)
Silicon Dioxide (SiO2)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Lemon Quartz (or Yellow Calcite)
Silicon Dioxide (SiO2) / Calcium Carbonate (CaCO3)
mineral
Gneiss (likely)
Gneiss
Metamorphic
Pearl
Calcium carbonate (CaCO3) - mainly Aragonite with Conchiolin
mineraloid
Granite
Phaneritic Felsic Igneous Rock
igneous
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Quartz
Quartz (SiO₂)
Mineral
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic