Igneous And Metamorphic Derivative (Weathered)

Milky quartz pebble

Quartz, silicon dioxide (SiO₂)

Unidentified weathered rock fragments

Likely mixed silicate rocks; specific identification requires testing

Gold Ore

Native Gold (Au) in Matrix

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz, feldspar, and biotite/amphibole

Weathered porphyritic granite or granitic gneiss

Quartz–feldspar–mica granitic rock; exact identification requires a fresh surface and mineral tests

Quartz

Quartz (SiO2)

Rounded quartz-rich pebble, likely granite or granitic gneiss

Granite/granitic rock composed mainly of quartz (SiO₂), feldspar, and minor dark mica or amphibole

Mica-bearing metamorphic rock, likely schist

Muscovite/biotite mica schist with quartz and feldspar

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Tumbled milky quartz (likely quartzite or chalcedony-rich stone)

Quartz, SiO₂

Milky quartz pebble

Quartz, silicon dioxide (SiO₂)

Gneiss (specifically a weathered Amphibolite or Garnet Gneiss)

Gneiss (complex silicate composition)

Weathered granite or granitic gneiss

Quartz–feldspar–mica granite; possibly gneiss if the faint foliation is genuine

Tumbled quartz-rich pebble

Quartz (SiO₂), possibly iron-stained or included quartz

Quartz fragment

Silicon Dioxide (SiO2)

Brown Garnet

Andradite or Almandine Garnet (general formula X3Y2(SiO4)3)

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests

Weathered quartz-bearing metamorphic rock

Likely quartz–feldspar schist or gneiss, possibly with iron-oxide alteration

Likely feldspar (weathered potassium feldspar)

K-feldspar, commonly orthoclase or microcline; KAlSi₃O₈

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Black Tourmaline

Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Milky quartz

Quartz, silicon dioxide (SiO₂)

Likely weathered quartz or feldspar grain

Uncertain; possibly quartz (SiO₂) or a feldspar mineral

Quartz-rich translucent stone, possibly quartzite or milky quartz

Quartz (SiO₂), potentially quartzite if the specimen is metamorphic

Rounded basalt cobble (probable)

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene

Banded Gneiss / Metamorphic River Pebble

Gneiss (Foliated Metamorphic Rock)

Pale greenish quartz-bearing rock, possibly serpentine or altered feldspar

Tentatively serpentinite-related rock (serpentine-group minerals) or altered granitic material; identification is uncertain from the photograph

Quartz fragment (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, such as granite, or recrystallized quartzite

Weathered quartz-rich cobble

Probable quartzite or quartz-rich metamorphic rock; exact identification requires a fresh surface and testing

Weathered granitic or metamorphic rock fragment

Indeterminate; likely quartz–feldspar–mica-bearing granitoid or gneiss

Granite with Epidote

Granite, containing quartz, feldspar, and epidote

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Black Sapphire (Basaltic Blue Sapphire)

Corundum (Al2O3)

Small pale mineral/rock fragment

Indeterminate; possibly weathered quartz, calcite, or light-colored limestone

Polished black stone, likely basalt or amphibolite

Basalt (fine-grained mafic rock), possibly amphibolite; primarily plagioclase and pyroxene/amphibole

Serpentinite

Serpentinite; chiefly serpentine-group minerals (lizardite, antigorite, chrysotile), often with magnetite and minor brucite

Black Tourmaline

Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Likely gabbro or dark amphibolite

Gabbro: coarse-grained mafic rock composed mainly of plagioclase and pyroxene; possible amphibolite: hornblende and plagioclase

Weathered brown quartz-rich pebble

Likely quartz (SiO₂) with iron-oxide staining; exact identification requires testing

Quartz Pebble

Quartz (SiO2)