Dark mafic rock, likely basalt
Basalt; chiefly plagioclase feldspar, clinopyroxene, and commonly olivine or iron oxides
igneous
Category
Synthetic (Not A Rock Or Mineral)
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Rounded basalt pebble
Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with minor olivine or magnetite
igneous
Likely basalt pebble
Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine
igneous
Vesicular basalt (possibly scoria)
Basalt; chiefly plagioclase feldspar, pyroxene, and often olivine, with volcanic glass
igneous
Green Schist
Greenschist (Chlorite Schist)
metamorphic
Chert (with Quartz Veining)
Microcrystalline Quartz (SiO2)
sedimentary
Garnet in Schist
Almandine Garnet in Mica-Schist (Fe3Al2(SiO4)3)
metamorphic
Chert (Jasper-like Silicate)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Mudstone variety with Oxidation)
Silicon dioxide (SiO2)
sedimentary
Amygdaloidal Basalt
Vesicular-Amygdaloidal Basalt (Mafic Extrusive)
igneous
Breciated Limestone with Calcite Veins
Sedimentary Breccia (CaCO3)
sedimentary
Granite
Granite (Plutonic Igneous Rock)
igneous
Gneiss (with Quartzite and Mica)
Gneiss
metamorphic
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock)
igneous
Quartz (River Pebble)
Silicon Dioxide (SiO2)
mineral
Geode with Iron-Stained Quartz/Calcite
Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) in Sedimentary Matrix
sedimentary
Banded Gneiss / Metamorphic River Pebble
Gneiss (Foliated Metamorphic Rock)
metamorphic
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
mineral
Black Tourmaline (Tumbled)
Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)4)
mineral
Small brown-gray mineral fragment
Indeterminate; possibly weathered quartz-, feldspar-, or iron-oxide-bearing rock
mineral
Quartz Vein / Quartzite
Silicon Dioxide (SiO2)
mineral
Agate (Carnelian type)
Silicon Dioxide (SiO2)
mineral
Rose Quartz
Silicon Dioxide (SiO2) with trace titanium, iron, or manganese
mineral
Clear Quartz Crystal
Silicon Dioxide (SiO2)
mineral
River Cobble (likely Siltstone or Sandstone)
Clastic Sedimentary Rock
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Granite
Intrusive Igneous Rock
igneous
River Stone (Sandstone or Siltstone)
Sedimentary Rock (Clastic)
sedimentary
Smoky Quartz with Chert
Silicon Dioxide (SiO2)
mineral
Pebble with Basaltic and Quartz-rich Banding
Polymictic Lithic Pebble
sedimentary
Tree Agate (also known as Dendritic Agate)
Silicon Dioxide with inclusions (SiO2 + Mn/Fe)
mineral
Sandstone
Sandstone (clastic sedimentary rock, composed predominantly of sand-sized minerals or rock fragments)
Sedimentary Rock
Zircon
Zircon (Zirconium Silicate - ZrSiO4)
mineral
Dalmatian Jasper
Microcrystalline Quartz with Arfvedsonite and Tourmaline inclusions
igneous
Banded Agate
Agate (Silicon Dioxide - SiO2)
mineral
Granite
Granite
igneous
Basalt with Quartz/Calcite Veins
Basalt (Aphanitic Mafic Volcanic Rock) with Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) inclusions
igneous
Gneiss
Gneiss (Foliated Metamorphic Rock)
metamorphic
Septarian Nodule (Dragon Stone)
Septarian concretion (composition: CaCO3 - Calcite, Aragonite, and Siderite/Limestone)
sedimentary
Basalt with Peridotite Xenolith
Mafic Igneous Rock with Peridotite Inclusion (Olivine-rich)
igneous
Limonite (with Goethite/Hematite glaze)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
mineral
Red Sandstone
Ferruginous Sandstone
sedimentary