Basalt

Lake Superior Agate

Cryptocrystalline Quartz (SiO2) with Iron impurities

Amethyst

SiO2 (Silicon Dioxide) - a variety of Quartz

Larimar

Blue Pectolite (NaCa2Si3O8(OH))

Amethyst

Amethyst (a variety of Quartz, SiO2)

River Pebble (Basalt or Gabbro)

Mafic Igneous Rock

Quartz Vein in Gneiss or Basalt

Milky Quartz (SiO2) within Metamorphic Host Rock

Drill Core (Basalt or Andesite)

Volcanic porphyry (mafic to intermediate)

Sunstone (variety of Feldspar)

Oligoclase Sunstone, Plagioclase Feldspar (Na,Ca)Al(Si,Al)Si2O8

Michigan Float Copper

Native Copper (Cu)

Labradorite

Labradorite (a variety of Plagioclase Feldspar), Na(AlSi3O8) to Ca(Al2Si2O8)

River Cobble (likely Basalt or Metagraywacke)

Non-specific water-worn lithic fragment

Pumice or Vesicular Basalt/Scoria (water-worn)

Vesicular volcanic rock

Porphyritic Andesite/Basalt or Diorite River Rock

Porphyritic Igneous Rock

Red Scoria (Lava Rock)

Scoria (Extrusive Igneous Rock / Mafic composition)

Amethyst (Druzy Cluster)

Silicon Dioxide (SiO2) with Fe3+ impurities

Banded Agate (specifically Lake Superior Agate type)

Silicon Dioxide (SiO2) - Microcrystalline Chalcedony

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) with host rock (often Schist or Basalt)

River Rock (Glacial Cobbles)

Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)

Lake Superior Agate

Banded Chalcedony (SiO2)

Amethyst (variety of Quartz)

SiO2 (Silicon Dioxide)

Chalcedony (Botryoidal or Agate nodule)

Silicon Dioxide (SiO2)

Pearl (with Peridot)

Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4

River Cobble (Basaltic/Andesitic)

Mafic Igneous Porphyritic Rock

Greenstone (Epidote/Chlorite-rich Metabasalt)

Greenschist / Epidosite (Ca2(Al,Fe)3(SiO4)3(OH))

Labradorite (tumbled)

Labradorite (a plagioclase feldspar mineral between anorthite and albite; chemical formula: (Ca,Na)(Si,Al)4O8)

Prehnite

Prehnite, Ca2Al2Si3O10(OH)2

Peridot (likely, based on color and appearance)

Olivine group mineral, specifically (Mg,Fe)2SiO4 (Forsterite-Fayalite solid solution series)

Amethyst

SiO2 (Silicon Dioxide)

Chinese Writing Stone

Porphyritic Basalt or Porphyritic Andesite with Feldspar phenocrysts (SiO2-rich Silicates)

Laterite (iron-rich nodule, possibly Bauxite as a subtype)

Laterite (composed of various minerals including goethite, hematite, gibbsite, etc.)

Nephrite Jade

Nephrite (a variety of the mineral actinolite within the amphibole group); Chemical Formula: Ca2(Mg,Fe)5Si8O22(OH)2

Granitic Pegmatite Intrusion in Host Rock

Pegmatite dike in amphibolite or schist

Amethyst

SiO2 (Silicon Dioxide)

Peridot

Olivine (specific variety: gem-quality forsterite), (Mg,Fe)2SiO4

Hypersthene (or Enstatite/Ferrosilite)

Orthopyroxene series (Mg,Fe)SiO3 - specifically, historically hypersthene (intermediate member) now referred to as Enstatite (Mg-rich) or Ferrosilite (Fe-rich)

Quartz Geode (partially formed/chalcedony with iron staining)

Quartz (SiO2) with Chalcedony (cryptocrystalline quartz) and likely Iron Oxides/Hydroxides

Amethyst

Amethyst is a variety of Quartz (SiO₂)

Larimar

Pectolite (Sodium Calcium Silicate Hydroxide) - (NaCa2(Si3O8)(OH))

River Cobble (likely Metasedimentary or Basalt)

Metamorphosed Siltstone or Altered Fine-grained Igneous Rock

Porphyry (specifically Porphyritic Basalt or Andesite)

Porphyritic extrusive igneous rock (Mg,Fe)2SiO4 (Olivine inclusions/Plagioclase Feldspar)

River Pebble (likely Quartzite or Basalt)

Quartzite (SiO2 as primary mineral)

Porphyry (likely Porphyritic Andesite or Basalt)

Porphyritic Igneous Rock