Mineral, Potentially A Rock With Chalcedony

Chalcedony or Chert/Jasper with secondary mineral staining

SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.

Likely quartz-rich chalcedony or agate fragment

Microcrystalline quartz (SiO₂), possibly iron-oxide-stained chalcedony/agate

Quartz-rich rock fragment

Microcrystalline quartz (SiO₂), possibly chalcedony or quartz-bearing breccia

Druzy quartz geode slice

Quartz, SiO₂, commonly lining a chalcedony-rich geode

Small rounded pebble (likely quartz or quartz-rich stone)

Uncertain; possibly microcrystalline quartz (SiO₂)

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if metamorphic

Quartz-rich translucent pebble, possibly iron-stained quartz or chalcedony

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)

Banded agate (likely chalcedony nodule)

Microcrystalline quartz, SiO₂; fibrous chalcedony with possible quartz bands

Agate (specifically Waterline or Onyx-type Agate)

Silicon Dioxide (SiO2) - variety Chalcedony

Rounded quartz-rich pebble

Likely microcrystalline quartz (chalcedony), possibly a weathered quartz or feldspar pebble

Chalcedony nodule (possibly agate)

Microcrystalline quartz, SiO₂; potentially banded agate

Quartz geode

Crystalline quartz, silicon dioxide (SiO₂), lining a volcanic geode

Gray chalcedony (possibly common opal)

Microcrystalline quartz, SiO₂; potentially hydrated silica, SiO₂·nH₂O

Milky Quartz Nodule / Geode precursor

Silicon Dioxide (SiO2)

Quartz-rich rock, possibly yellow chalcedony or weathered quartzite

Quartz (SiO₂), likely microcrystalline chalcedony with iron-oxide staining

Geode (unopened) or Calcareous Nodule

Siliceous or Calcareous Concretion/Nodule

Honey-colored quartz-rich stone, possibly chert or chalcedony

Microcrystalline silica (SiO₂), identification uncertain from photograph

Pale blue-gray quartz-rich pebble (tentative)

Quartz, SiO₂, possibly chalcedony or a weathered metamorphic fragment

Milky quartz pebble

Quartz (SiO₂), cryptocrystalline to coarse microcrystalline variety

Gray chalcedony or quartz fragment

Microcrystalline quartz, SiO₂ (tentative)

Small rounded pebble, likely quartz-rich river stone

Indeterminate; likely quartz/chert-bearing lithic clast

Agate Geode Nodule

Chalcedony / Quartz (SiO2)

Likely weathered quartz-rich stone

Indeterminate; possibly quartz-bearing granite or milky quartz

Blue-gray mineral/rock fragment

Indeterminate; possibly azurite-bearing material, blue chalcedony, or dyed/coated stone

Small polished cabochon, likely green/gray beryl or agate

Uncertain from image; possible beryl (Be₃Al₂Si₆O₁₈) or chalcedony (SiO₂)

Blue-gray quartz-bearing rock, likely dumortierite quartz or silicified metamorphic rock

Quartz (SiO₂) with probable dumortierite and iron-oxide inclusions

Tumbled reddish-brown stone, possibly jasper or quartzite

Uncertain; likely microcrystalline quartz (SiO₂), potentially iron-stained jasper

Geode Nodules / Chert Pebble

Silicon Dioxide (SiO2) / Quartz concretion

Geode with Quartz/Chalcedony

Silicon Dioxide (SiO2)

Quartz Vein in Basalt or Slate

Hydrothermal quartz vein traversing mafic host rock

Milky quartz vein fragment

Quartz (SiO₂), likely massive or vein quartz with minor iron-oxide/clay inclusions

Chert (Chalcedony/Agate variety)

Microcrystalline Quartz (SiO2)

Copper-bearing Quartz Vein in Host Rock

Quartz with Malachite/Chrysocolla staining

Mixed rock and mineral collection

Unidentified assortment of geological specimens; individual species cannot be determined from the image

Unidentified small rounded mineral/rock fragment

Indeterminate from image; possibly quartz or chalcedony with iron-oxide staining

Geode (Unopened)

Siliceous Septarian Concretion / Geode (SiO2)

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly chalcedony or quartzite

Agate Geode (Unopened)

Cryptocrystalline Quartz (SiO2) with Chalcedony

Chert (Common Opal/Agatized Rock)

Microcrystalline Quartz (SiO2) with potential Chalcedony/Opaline silica

Botryoidal quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Milky quartz-bearing rock, likely quartzite or silicified limestone

Quartz (SiO₂), possibly in a quartzite or chalcedony-rich matrix

Weathered chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony