Mineral, Possibly Rock Fragment Containing A Mineral

Weathered fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Mixed rough mineral specimens, likely quartz-bearing rocks

Probable quartz (SiO₂), with possible feldspar, iron oxides, and altered host rock

Unidentified dark pebble

Undetermined; possibly polished basalt, chert, or iron-rich stone

Porous limestone

Calcite-rich limestone (CaCO₃), possibly fossiliferous or chalky limestone

Small quartz-rich rock fragment

Likely quartz-bearing granite, pegmatite, or quartzite; exact identification is uncertain from the photograph

Small quartz-rich rock fragment

Likely quartz (SiO₂), possibly a pale granite or feldspar-bearing fragment

Tumbled fossil-bearing limestone or chert

Microcrystalline calcite (limestone), possibly silicified; fossil fragments visible

Uncertain green-brown mineral fragment

Possibly epidote, chlorite, or altered amphibole; exact identification requires testing

Milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered quartz-bearing rock, possibly calcite vein fragment

Indeterminate; likely quartz (SiO₂) with carbonate minerals such as calcite (CaCO₃)

Weathered volcanic rock, likely altered basalt/andesite

Fine-grained mafic to intermediate volcanic rock; possible chlorite–calcite alteration

Quartz-rich rock, likely milky quartz with iron staining

Quartz (SiO₂), possibly a quartz vein fragment

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially granitic, or recrystallized quartzite

Likely iron-rich rock fragment

Indeterminate; possibly limonite/goethite-stained rock, with no diagnostic features visible

Jasper-rich breccia (likely iron-stained jasper)

Silicified breccia composed mainly of microcrystalline quartz (SiO₂), with hematite/goethite and possibly iron-rich clay minerals

Likely quartz-bearing rock or mineral fragment

Indeterminate; possibly quartz (SiO₂) with iron-oxide staining and darker matrix

Likely pyrite-bearing rock fragment

Pyrite, FeS₂, possibly in a dark host rock

Weathered sedimentary rock, possibly sandstone

Indeterminate clastic sediment; probable quartz-rich sandstone

Weathered brown rock fragment, possibly iron-rich basalt or breccia

Tentatively basaltic rock; exact identification requires testing

Likely quartz-rich stone or pale feldspar fragment

Indeterminate; possibly quartz (SiO₂) or feldspar (KAlSi₃O₈–NaAlSi₃O₈)

Weathered quartz-rich pebble

Likely granitic or feldspathic clast; chiefly quartz (SiO₂) and feldspar

Ironstone / iron-oxide-rich rock fragment

Likely limonite/goethite-rich ironstone; exact identification is not possible from the image alone

Concrete

Anthropogenic Conglomerate

Sandstone (Quartzose)

Arenite (SiO2)

Brecciated jasper, possibly rainforest jasper or brecciated rhyolite

Brecciated microcrystalline quartz (SiO₂), commonly called jasper; the green portions may contain epidote, chlorite, or iron-bearing silicates, while red-brown areas are typically hematite or other iron oxides

Likely weathered iron-rich rock or mineral fragment

Indeterminate; possibly limonite/goethite-rich material with quartz or feldspar

Mixed rock specimens; likely pink feldspar/quartz and a dark, mica-bearing rock

Tentative visual identification: pink K-feldspar–quartz-rich granite/pegmatite fragments and a dark amphibole- or biotite-rich metamorphic rock; exact identification is uncertain from the image

Possible weathered metal-rich rock or slag fragment

Uncertain; possibly iron-oxide-rich breccia or industrial slag

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Likely raw rose quartz or pink feldspar fragment

Quartz (SiO₂), possibly pink feldspar such as orthoclase

Pale quartz-rich stone, possibly calcite

Likely quartz (SiO₂) or calcite (CaCO₃); image resolution prevents confident separation

Uncertain dark gray-brown rock fragment

Indeterminate; possibly weathered chert, serpentine, or iron-stained quartzite

Vesicular basalt (possibly weathered lava rock)

Basalt; chiefly plagioclase, clinopyroxene, and olivine, with iron oxides

Weathered quartz- or feldspar-rich rock fragment

Indeterminate light-colored silicate rock; possibly quartz or feldspar in a granitic fragment

Likely quartz-rich pebble fragment

Quartz (SiO₂), possibly milky quartz or quartzite; the photo is insufficient to distinguish them confidently

Tumbled red jasper and related pebbles

Jasper, a microcrystalline variety of quartz (SiO₂), commonly containing hematite/goethite and other iron oxides

Metallic sulfide ore, likely galena-bearing rock

Galena (lead sulfide, PbS), possibly with pyrite or other sulfides

Likely weathered quartz-rich pebble

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

Sandstone

Arenite (SiO2 primarily)

Pegmatitic granite (likely quartz–feldspar rock)

Granitic pegmatite, composed mainly of quartz (SiO₂) and feldspar

Likely quartz-bearing rock or mineral fragment

Probable quartz (SiO₂), possibly a weathered pegmatite or chalcedony fragment

Weathered quartz-bearing rock, possibly gneiss or quartzite

Indeterminate; likely quartz-rich metamorphic rock containing quartz and feldspar