River Rock / Stream Pebble
Fluvial Clast / Rounded Sedimentary Particle
Sedimentary Rock (possibly composed of various minerals)
Category
Mineral, Often A Rock Given Its Aggregate Nature
Browse mineral, often a rock given its aggregate nature specimens identified by the Rock Identifier community.
Quartz (River Pebble)
Silicon Dioxide (SiO2)
mineral
Sandstone (Weathered Cobble)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Yellow Quartzite River Stone
Quartzite (primarily SiO2)
metamorphic
Quartz (River Pebble)
Silicon Dioxide (SiO2)
mineral
Siltstone with Quartz Vein
Siltstone (primarily SiO2, Al2O3, Fe2O3)
sedimentary
Yellow Quartz (Citrine/Lemon Quartz)
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss (a type of metamorphic rock)
Metamorphic Rock
Basalt (Vesicular)
Vesicular Basalt
Igneous
Tiger's Eye (Brown/Dark variety)
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions)
metamorphic
Obsidian (likely Golden Sheen Obsidian or Rainbow Obsidian, given the subtle sheen visible on some beads)
Obsidian (volcanic glass, predominantly SiO2 with various impurities)
Igneous
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.
Igneous
Slag
Ferrous Slag (Amorphous calcium-magnesium-aluminum silicates)
igneous (artificial/anthropogenic)
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Coquina / Shelly Limestone
Coquina (calcium carbonate, CaCO3)
sedimentary
Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Red Jasper
Jasper (Silicon Dioxide, SiO2 with iron oxide impurities)
mineral
Chrysocolla on Matrix
Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Milky Quartz with Matrix
Quartz (Silicon Dioxide, SiO2)
mineral
Pyrite in Matrix (likely Quartz or Schist matrix)
Iron Sulfide (FeS2)
mineral
Basalt with vesicles/amygdules
Basalt (containing volcanic glass and plagioclase)
igneous
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock)
igneous
Quartz Vein in Gneiss or Basalt
Milky Quartz (SiO2) within Metamorphic Host Rock
Metamorphic or Igneous with Mineral Inclusion
Rough Quartz (or Quartzite pebble)
Silicon Dioxide (SiO2)
mineral
Quartz (River Siltstone Quartzite Pebble)
Silicon Dioxide (SiO2)
metamorphic
Jasper (likely a variety of Brecciated Jasper or a patterned variety)
Silicon dioxide (SiO2)
Mineral
Basalt
Basalt (composition of plagioclase, pyroxene, and olivine)
igneous
Serpentinite
Serpentinite (composed primarily of serpentine-group minerals like antigorite, chrysotile, and lizardite; chemical formula varies but generally Mg3Si2O5(OH)4)
Metamorphic Rock
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
mineral
Quartzite (Milky Quartz pebble)
Silicon Dioxide (SiO2)
metamorphic
Basalt
Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
Igneous
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
mineral
Chert (Holey Stone)
Microcrystalline Quartz (SiO2)
sedimentary
Dyed Agate (Tumbled)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Yellow Quartzite (River Pebble)
Quartzite (SiO2)
metamorphic
Gold Nugget
Native Gold (Au)
mineral
Quartz (Milky or White Quartz)
Silicon Dioxide (SiO2)
mineral
Quartz (Vein Quartz)
Silicon Dioxide (SiO2)
mineral
Sandstone (Quartzose)
Arenite (composed primarily of SiO2)
sedimentary
Milk Quartz (with Iron staining)
Silicon Dioxide (SiO2)
mineral
Conglomerate
Conglomerate rock
sedimentary
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral