Non Geological

Pearl necklace with small blue-green gemstone accents

Pearls: nacre, chiefly aragonite (CaCO₃) and conchiolin; accents appear to be turquoise or similar opaque blue-green stone

Green aventurine (tumbled)

Quartz, SiO₂, with fuchsite or other mica inclusions

Libyan Desert Glass

Libyan Desert Glass (SiO2 with trace elements)

Weathered agate or chalcedony nodule

Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining

Manganese-coated Sandstone

Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)

Anthracite Coal

Anthracite

Gold Ore in Matrix

Native Gold (Au) in Quartz/Limonite host rock

Faceted purple-blue beads, likely synthetic glass or treated gemstone

Indeterminate; possible synthetic corundum, synthetic spinel, or dyed quartz (SiO₂)

Green glassy mineral specimen, likely rough emerald or green fluorite

Tentatively beryl (Be₃Al₂Si₆O₁₈), emerald variety; synthetic/man-made glass cannot be excluded from the photograph

Polished dark gemstone, likely hematite or magnetite

Hematite (Fe₂O₃) or magnetite (Fe₃O₄); exact identification requires testing

N/A (Non-Geological Object)

Blue Slag Glass

Amorphous Silica (Industrial byproduct)

Rounded dark river stone

Likely basalt or fine-grained andesite; exact identification requires testing

Pearl-and-gemstone insect brooch

Pearl: nacre (aragonite, CaCO₃); colored stones are likely synthetic or natural corundum/spinel/glass, not determinable from the image

Obsidian

Obsidian (volcanic glass)

Tektite (Indochinite)

Impact Glass (SiO2 + Al2O3)

N/A - Image does not contain a rock or mineral

Anthropogenic textile material

Glass / Silicon Dioxide (Man-made)

SiO2 (Amorphous Silicon Dioxide)

Polymer Clay (Mock Mineral)

Polyvinyl chloride (PVC) with plasticizers and pigment

Quartzite

Metamorphic rock (SiO2)

Black Obsidian

Volcanic Glass (SiO2)

Quartz-rich metamorphic pebble

Milky quartz with possible feldspar and mica; likely quartzite or quartz-veined metamorphic rock

Likely tumbled iron-stained quartz or chalcedony

Quartz/chalcedony (SiO₂), possibly limonite-coated

Cullet Glass (Slag Glass)

Amorphous Silicon Dioxide (SiO2) with metallic oxide impurities

Quartzite Pebble

Quartzite

Black Obsidian

Volcanic Glass (SiO2)

Obsidian

Volcanic Glass (Rich in SiO2)

Obsidian

Obsidian (Volcanic Glass)

Obsidian

Obsidian (Volcanic Glass, complex silicate)

Obsidian

Amorphous volcanic glass (primarily SiO2)

Polished orbicular jasper (likely ocean jasper)

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron oxides and other silicate inclusions

Banded Sandstone (Liesegang Rings)

Sedimentary sandstone with Iron oxide precipitates

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Slag Glass

Vitreous Silicate Residue

River Siltstone / Mudstone Pebble

Siltstone (composed of mixed silicate and carbonate minerals)

Rounded sandstone cobble

Clastic sandstone, likely quartz-rich (quartz arenite or arkose)

Rough Green Beryl (Emerald variety)

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Cupronickel (on a 1981 Mexico 20 Pesos coin)

Copper-Nickel Alloy (Cu75Ni25)

Black Tourmaline (Schorl)

Sodium Iron Aluminum Borosilicate (NaFe2+3Al6(BO3)3Si6O18(OH)4)

Obsidian

Volcanic Glass (Amorphous Silicon Dioxide , SiO2)

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Bull Quartz

Quartz (Silicon Dioxide - SiO2)