Mineral, Specifically A Rock Fragment

Travertine (Tufa)

Chemical Limestone (CaCO3)

Pegmatitic granite, possibly potassium-feldspar-rich

Coarse-grained granite; mainly quartz (SiO₂), potassium feldspar (KAlSi₃O₈), plagioclase, and biotite/hornblende

Banded Greywacke

Greywacke (Lithic wacke)

Quartz Geode Fragment

Silicon Dioxide (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.

Blue Apatite

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

Amethyst (Chevron or Banded variety)

Silicon Dioxide with Iron impurities (SiO2)

Bivalve Fossil (Shell Fragment)

Class Bivalvia (Calcium Carbonate - CaCO3)

Pink Granite

Felsic intrusive igneous rock

Likely iron-rich rock or metallic mineral fragment

Uncertain; possibly limonite/goethite-rich material or weathered iron meteorite fragment

Sandstone

Sedimentary rock composed mainly of quartz sand

Rounded brown river pebble

Indeterminate lithic fragment; possibly weathered sandstone, mudstone, or basalt

Quartz crystal (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Unidentified weathered rock, possibly quartz-bearing granite or rhyolite

Indeterminate; likely quartz–feldspar-rich silicate rock

Pink Granite

Phaneritic Quartz-Feldspar Plutonic Rock

Likely weathered quartz-bearing rock (uncertain identification)

Possibly quartz-rich granite or granitic aplite; exact identification requires a clearer, larger image and tests

Quartz (Gravel fragment)

Quartz (Silicon Dioxide, SiO2)

Sandstone

Clastic Sedimentary Rock

Sandstone

Sedimentary Clastic Rock

Sandstone (with Siltstone/Greywacke variations)

Sedimentary Rock (Clastic)

Dragon Vein Agate

Silicon Dioxide (SiO2)

Quartz (Herkimer Diamond variant)

Silicon Dioxide (SiO2)

Amethyst

SiO2 (Silicon Dioxide with Iron impurities and natural radiation influence)

Druzy Quartz Geode Fragment

Silicon Dioxide (SiO2)

Sandstone

Clastic sedimentary rock

Red Sandstone

Sedimentary Quartz Arenite / Arkose

Rose quartz

Quartz, silicon dioxide (SiO₂)

Quartzite Fragment

Crystalline Silicon Dioxide (SiO2)

Fossilized Bone Fragment

Permineralized Vertebrate Bone (Hydrox yapatite replaced by Silica or Calcite)

Pink Granite

Granite (enriched in Potassium Feldspar)

Sandstone

Sedimentary Rock (Quartz arenite)

Agate (specifically a Yellow/Honey Agate)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Basalt

Basalt (composition predominately plagioclase feldspar and pyroxene)

Granite Fragment

Felsic Plutonic Rock (Granite)

Granite

Granite (composed mainly of Quartz, Alkali Feldspar, and Plagioclase)

Chalcedony (likely agate/chert fragment)

Microcrystalline quartz, SiO₂

Silver-gray metallic ore, possibly galena-bearing rock

Likely galena (PbS) in a host rock, but identification is uncertain from the photograph

Amygdaloidal Basalt

Amygdaloidal Basalt

Quartz-bearing iron-stained breccia

Brecciated quartz/quartzite with iron oxides, chiefly SiO₂ with hematite/goethite and possible feldspar or host-rock fragments

Sandstone Pebble

Sedimentary Rock (Quartzose Sandstone)

Sandstone

Arenite (SiO2 primarily)

Gneiss (specifically Epidote-Quartz Gneiss)

Gneiss containing Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) and Quartz (SiO2)