Mineral, Sediment

Weathered volcanic rock fragment

Likely andesite or basaltic-andesite; exact identification requires fresh surface and testing

Jasper (likely Polychrome or Mookaite variants)

Silicon Dioxide (SiO2) with iron oxide and hydroxide inclusions

Limonite Concretion (Goonie or Rattlestone)

Limonite (FeO(OH)·nH2O)

Rounded quartz-rich pebble

Likely milky quartz or quartzite (SiO₂)

Fossil-bearing sedimentary rock (possible bone or shell fossil)

Unidentified fossiliferous sedimentary matrix; exact fossil and host rock cannot be determined from the image

Desert Rose

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Iron-rich brown stone, possibly weathered chert or ironstone

Undetermined; likely iron-oxide-bearing silica-rich rock (chert/ironstone)

Polished septarian nodule

Septarian concretion, chiefly calcite and aragonite in a clay-rich carbonate matrix

Concretion or weathered iron-rich rock

Likely limonite/goethite-rich concretion; exact identification requires testing

Pale quartz-rich pebble

Likely vein quartz (SiO₂); exact identification is uncertain from the photograph

Weathered gray sandstone or siltstone

Clastic siliciclastic rock, primarily quartz and feldspar grains cemented by silica or carbonate

Rounded metallic-looking pebble, likely iron-rich rock or slag

Uncertain; possible limonite/goethite-rich ironstone, hematite-bearing material, or industrial slag

Likely iron-rich sandstone or ironstone fragment

Indeterminate ferruginous sedimentary rock; iron oxides may include hematite (Fe₂O₃) or goethite (FeO(OH))

Bivalve Internal Mold Fossil

Steinkern (Bivalvia mold)

Iron-rich weathered stone, possibly hematite-rich ironstone

Hematite/goethite-bearing ironstone; predominantly Fe₂O₃ and FeO(OH)

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

Ironstone Concretion

Ironstone (primarily Siderite or Limonite)

Fossilized sea urchin test (likely sand dollar fragment or echinoid fossil)

Echinoidea; calcitic echinoderm skeleton, chiefly CaCO₃

Sandstone

Arenite

Ironstone concretion

Siderite or Limonite concretion (FeCO3 or FeO(OH)·nH2O)

Sandstone Concretion

Arenaceous concretion (primarily SiO2 with Fe2O3 staining)

Sandstone

Clastic Sedimentary Rock (composed mostly of SiO2)

Ironstone Concretion

Siderite or Hematite Concretion (FeCO3 or Fe2O3)

Ironstone Concretion

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Sandstone (with Iron Siderite Concretion)

Arenite with Ironstone Concretion (FeCO3)

Jasper

Silicon dioxide (SiO2)

Bivalve Fossil (Internal Mold/Steinkern)

Class Bivalvia (Fossilized Mold)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Polished brown chert or jasper pebble

Microcrystalline quartz (SiO₂), likely iron-stained chert/jasper

Fossilized Echinoid (Sea Urchin) or Brachiopod

Echinoidea / Invertebrate Fossil

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Banded Chert / Sandstone Pebble

Microcrystalline Quartz (SiO2) / Silicified Sandstone

Weathered garnet-bearing rock (possibly garnet schist)

Garnet-bearing mica schist; likely almandine garnet (Fe₃Al₂(SiO₄)₃) with mica and quartz

Small rounded orange-brown stone, likely iron-stained quartzite or sandstone

Indeterminate; probable quartz-rich sandstone/quartzite with iron-oxide staining

Weathered sulfide-bearing ore specimen

Likely pyrite- and/or chalcopyrite-bearing quartz–iron-oxide rock; exact identification requires testing

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

Small rounded pebble, likely quartz-rich stone

Indeterminate; possibly quartzite or light-colored granitoid, composed mainly of quartz and feldspar

Iron-rich reddish rock, possibly weathered basalt or ironstone

Indeterminate; likely oxidized mafic rock containing iron oxides and silicate minerals

Polished iron-rich jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored by iron oxides

Quartz fragment (likely milky quartz)

Quartz, silicon dioxide (SiO₂)