Sedimentary To Metamorphic

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Limonite Pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O replacing Pyrite FeS2

Weathered quartz-rich rock, likely sandstone or quartzite

Quartz-dominated lithic fragment; probable quartz sandstone (SiO₂)

Feldspar-rich Quartzite

Metamorphic Quartz-Feldspar Aggregate (SiO2 + KAlSi3O8)

Banded Chert / Banded Jasper (likely a variety of Chert/Chalcedony)

Chert (microcrystalline quartz)

Sandstone or Quartzite

Arenite (if sedimentary) / Quartzite (if metamorphic)

Quartz (chalcedony variety) or Limestone with Quartz Veins

SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)

Pyrite (or Fool's Gold)

Pyrite (FeS₂)

Quartzite / Sandstone / Chert Mix

Silicon Dioxide (SiO2)

Tumbled reddish-brown pebble, likely sandstone or iron-rich quartzite

Probable ferruginous sandstone (quartz-rich; SiO₂ with iron oxides), possibly quartzite

Jasper

Chalcedony (Microcrystalline Quartz) - SiO2

Carnelian

Carnelian (a variety of Chalcedony, SiO ₂)

Sandstone, Quartzite, and River Pebbles

Silicon Dioxide (SiO2) based Sedimentary/Metamorphic structures

Jasper or Red Quartzite

SiO2 (Silicon Dioxide with iron oxide impurities)

Jasper and Quartzite mix

Silicon Dioxide (SiO2) with impurities

Worn quartz-rich pebble, likely chert or quartzite

Microcrystalline quartz (SiO₂), possibly quartzite

Mixed Agate and Lapis Lazuli Bracelet

Chalcedony (SiO2) and Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Glacial Erratic (Sandstone/Quartzite)

Glacial Erratic specimen (likely Orthoquartzite or Feldspathic Sandstone)

Limonite-stained Quartz / Quartzite

Silicon Dioxide (SiO2) with iron hydroxides (FeO(OH)·nH2O)

Greenstone / Chert

Cryptocrystalline Quartz (SiO2) or Altered Basalt

Red Jasper (possibly with Quartz or Hematite)

Silicon Dioxide (SiO2) with iron oxide impurities

Rounded river pebble, likely quartz-rich sandstone or fine-grained quartzite

Indeterminate quartz-rich lithic clast; likely quartz sandstone (SiO₂-rich) or quartzite

River Pebbles (Sandstone and Quartzite)

SiO2 (Quartz) dominated clastic rocks

Micaceous Sandstone or Quartzite

Sandstone (lithified quartz grains, often with mica) or Quartzite (metamorphosed sandstone)

River Pebble (likely Quartzite or Chert)

Silicon Dioxide (SiO2) crystal conglomerate

Unidentified River Rock or Mudstone

N/A (Generic rock fragment)

Pyrite-bearing rock (likely pyrite in a quartz or sulfide-rich matrix)

Pyrite, FeS₂; the gray host may be quartz, carbonate, or another sulfide-bearing rock

Probable amber fragment

Amber (fossilized plant resin; chiefly amorphous organic resin, commonly dominated by succinite)

River Stone / Pebble

Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)

Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)

Quartz (SiO₂)

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Tiger’s eye

Quartz variety, primarily silicon dioxide (SiO₂); fibrous quartz pseudomorph after crocidolite asbestos

Quartz with Iron Stains

Quartz (SiO2) with iron oxide/hydroxide staining

Mixed Rock Collection (Pebbles and Stones)

Various geological specimens

Chalcedony (Banded/Mottled Variety)

Chalcedony (a cryptocrystalline variety of Quartz, SiO2)

Drill Core Samples (Varied Lithology)

Multi-lithological core samples (containing potential granite, marble, and phyllite/schist sequence)

Mixed collection of minerals and rocks (Jasper, Carnelian, Granite, and Quartz)

Silicon Dioxide (SiO2) with varying impurities for silicates and igneous aggregates

Mixed Tumbled Stones (Mostly Agate, Jasper, and Quartz)

Silicon Dioxide (SiO2)

Mixed Rock and Mineral Collection

Various geological specimens

Earth

Terra / Earth

Engineer Quartz/Quartzite

SiO2 (Silicon Dioxide with binders)

Shale or Argillite

Shale (fine-grained clastic sedimentary rock) or Argillite (low-grade metamorphic rock derived from shale)