Mineraloid (Human Made Geological Specimen)

Moqui Marble

Ironstone Concretion (Goethite/Hematite)

Bornite (Peacock Ore)

Bornite (Cu5FeS4)

Fossil Coral (Petoskey Stone / Rugose Coral)

Hexagonaria percarinata (Order: Rugosa, Fossilized Calcium Carbonate CaCO3)

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Quartz on Basalt

Silicon Dioxide (SiO2) on Mafic Igneous Rock

Fossilized Coral

Cnidaria (Anthozoa), often replaced by Calcium Carbonate (CaCO3) or Silica (SiO2)

Pink Stained Rock (Likely Quartzite or Sandstone with Iron Oxide Staining)

Quartzite (metamorphic) or Sandstone (sedimentary); coloration likely due to hematite or other iron oxides.

Dyed Agate

Silicon Dioxide (SiO2) with artificial pigment

Pyrite (or Fool's Gold)

Pyrite (FeS₂)

Banded Flint / Chert

Silicon Dioxide (SiO2)

Chert (Tripolitic Chert / Flint Nodules)

Microcrystalline Quartz (SiO2)

River Cobble (likely Sandstone or Siltstone type)

Sandstone or Siltstone (common rock types that form river cobbles)

Sandstone

Arenite or Sandstone

Mahogany Obsidian or Red Jasper

Silicon Dioxide with Iron Oxide (SiO2+Fe2O3)

Chert (Jasper-like)

SiO2 (Cryptocrystalline Quartz)

Chert (Gravel pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (often called Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)

Botryoidal Chalcedony with Calcite

Chalcedony (SiO2 with accessory minerals, likely CaCO3)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (principally Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Agatized Petrified Wood

Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood

Petrified Wood

Silicified Wood (SiO2)

Chert (variant Flint/Novaculite)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Geode/Cluster

Quartz (SiO2)

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Rutilated Quartz

SiO2 with TiO2 inclusions (Rutile)

Laterite (iron-rich nodule, possibly Bauxite as a subtype)

Laterite (composed of various minerals including goethite, hematite, gibbsite, etc.)

Dark-colored Igneous Rock (likely Basalt or Diabase)

Basalt (extrusive igneous) or Diabase (intrusive igneous)

Agate

Agate (a cryptocrystalline variety of Quartz, SiO₂)

Smoky Quartz

Smoky Quartz (SiO2)

Chert (Chert Nodule with Cortex)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Kunzite

Spodumene (LiAlSi2O6), variety Kunzite

Wishing Stone (Basalt or Siltstone with Quartz/Calcite Vein)

Basalt (SiO2+MgO+FeO) or Siltstone with a Quartz (SiO2) or Calcite (CaCO3) vein

Botryoidal Quartz / Calcite Geode crust

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

Fossilized Coral (Petoskey-like or Favosites)

Anthozoa (Fossilized Coral)

Petrified Wood

Silicified Wood (primarily Silicon Dioxide, SiO2)