Mineral (Native Element Alloy)

Quartzite Pebble

Quartzite (primarily SiO2)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Blue Quartz (Aventurine)

Silicon Dioxide (SiO2) with fibrous inclusions (commonly Dumortierite)

Quartz Pebble

Silicon Dioxide (SiO2)

Blue Apatite

Apatite (Ca5(PO4)3(F,Cl,OH))

Chert (Red Jasper variant)

Microcrystalline Quartz (SiO2)

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Geode (unopened)

SiO2 - Chert-shelled concretion (mostly Quartz)

Corundum (Ruby Variety)

Corundum (Al2O3)

Granite

Phaneritic Igneous Rock (Granite)

Amygdaloidal Basalt with Epidote

Vesicular Basalt with secondary Epidote/Quartz mineral infill

Quartzite River Rock with Dendrites

Metamorphosed Quartz-rich Sandstone with Manganese Oxide (MnO2) inclusions

Honeycomb Calcite

Calcite (Calcium Carbonate, CaCO3)

Pink Granite (with Potassic Feldspar and Quartz)

Felsic Intrusive Igneous Rock (Granite)

Dark-colored Igneous Rock (likely Basalt or Diabase)

Basalt (extrusive igneous) or Diabase (intrusive igneous)

Black Sapphire

Corundum (Al2O3 with iron and titanium impurities)

Milky Quartz

Silicon Dioxide (SiO2)

Kimberlite with Diamond

Kimberlite (Diamond formula: C)

Diorite (Polished River Pebble)

Diorite (Intermediate intrusive igneous rock)

Gneiss

Gneiss (Metamorphic rock composed primarily of quartz, feldspar, and mica)

Mica Schist with Quartz

Mica-Quartz Schist (Muscovite subclass)

Diorite

Diorite (plutonic igneous rock)

Milky Quartz

Silicon Dioxide (SiO2)

Howlite (Tumbled)

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Rose Quartz

SiO2 (Silicon Dioxide)

Shale

Fissile Mudrock (Clay-rich Sedimentary Rock)

Rhodochrosite

Manganese Carbonate (MnCO3)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Iolite (Cordierite)

Magnesium Iron Aluminum Silicate (Mg,Fe)2Al4Si5O18

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock

Dyed Blue Agate

Cryptocrystalline Quartz (SiO2)

Sandstone

Sandstone (arenite is a more specific geological term for a clean sandstone, while wacke refers to a dirty sandstone with significant matrix)

Strawberry Quartz

Quartz (SiO2) with inclusions of Goethite or Hematite

Vesicular Basalt with Secondary Mineral Inclusions

Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Azurite-Malachite (often a mixed specimen)

Azurite: Cu3(CO3)2(OH)2; Malachite: Cu2(CO3)(OH)2. The specimen appears to be a natural mixture or intergrowth of these two minerals.

Limonite (Iron Stone/Ocher)

Limonite (FeO(OH)·nH2O)

Schorl (Black Tourmaline) in Matrix

Sodium Iron Aluminum Borosilicate Hydroxide (NaFe2+3Al6Si6O18(BO3)3(OH)3OH)

Pyrite

Iron Disulfide (FeS2)

Greenstone

Greenschist (containing chlorite, epidote, and actinolite)

Geode with Iron-Stained Quartz/Calcite

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) in Sedimentary Matrix