Marble

Chert (specifically Gray Chert)

Chert (SiO2)

Chalk

Calcium Carbonate (CaCO3)

Chalk (Limestone)

Calcium Carbonate (CaCO3)

Chert

Microcrystalline silica (SiO2)

Basalt River Stone

Basalt

Limestone

Calcium Carbonate (CaCO3)

Diamond (Macled/Crystal fragment)

Carbon (C), isometric crystal system

Porphyritic Rhyolite (Red Rhyolite)

Rhyolite (Porphyry)

Basalt (Weathered)

Extrusive mafic volcanic rock

Orange Tabby (Felis catus)

Felis silvestris catus (variety: Red Mackerel Tabby)

Limestone Gravel

Calcium Carbonate (CaCO3)

Chalky Limestone

Carbonate sedimentary rock (CaCO3)

Fossiliferous Limestone

Biogenic Calcium Carbonate (CaCO3)

Limestone (specifically Fossiliferous Limestone)

Calcium Carbonate (CaCO3)

Chert (Flint) with Glauconite

Microcrystalline Quartz (SiO2)

Porphyritic Basalt

Basalt (with plagioclase phenocrysts)

Eclogite

Eclogite (Pyrope garnet and Omphacite pyroxene)

Limestone (specifically Chalky Limestone)

Calcium Carbonate (CaCO3 / Calcite)

Crinoid Stem Fossil (in matrix)

Crinoid (Class Crinoidea)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Honey Calcite

Calcite (Calcium Carbonate, CaCO3)

Serpentinite

Serpentinite (group of minerals: Antigorite, Lizardite, Chrysotile)

Fossiliferous Limestone with Crinoid stems

Limestone (CaCO3) containing Crinoidea fossils

Limestone (specifically Marl or Chalk)

Calcium Carbonate (CaCO3)

Chert (specifically brown Chert or Jasper)

Microcrystalline Quartz (SiO2)

Peridotite

Peridotite (predominantly Olivine and Pyroxene)

Fossilized Solitary Rugose Coral (Horn Coral)

Order: Rugosa (e.g., Grewingkia or Heliophyllum); composed of Calcite (CaCO3) or Silica (SiO2)

Ammonite Fossil

Ammonoidea (primarily composed of Calcite, CaCO3)

Red Coral (Precious Coral)

Corallium rubrum (Calcium Carbonate, CaCO3)

Chert

Microcrystalline Quartz (SiO2)

Chert pebble

Cryptocrystalline Quartz (SiO2)

Fossiliferous Limestone (Crinoid stem fossils)

Sedimentary Limestone with Crinoidea ossicles

Gray Limestone Pebble

Calcium Carbonate (CaCO3)

Fossilized Coral (Petoskey Stone / Favosites)

Favosites (extinct genus of tabulate coral)

Chalk

Calcium Carbonate (CaCO3)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Limestone

Calcium Carbonate (CaCO3)

Serpentinite

Serpentinite (composed largely of serpentine group minerals including antigorite, lizardite, and chrysotile)

Fossiliferous Limestone (Coral Fossil)

Scleractinian Coral in Calcium Carbonate (CaCO3)

Chert Arrowhead

Microcrystalline Quartz (SiO2)

Fossiliferous Limestone

Biomicrite / Limestone with fossils

Pallasite Meteorite (Sliced and Polished)

Pallasite (Iron-Nickel Matrix with Olivine crystals)