Prehnite
Prehnite - Ca2Al(AlSi3O10)(OH)2
mineral
Category
Man Made Byproduct (Often Mistaken For Obsidian Or Emerald)
Browse man made byproduct (often mistaken for obsidian or emerald) specimens identified by the Rock Identifier community.
Garnet (likely Almandine, Pyrope, or a blend)
Garnet group minerals: X3Y2(SiO4)3, where X and Y represent various metal ions (e.g., Almandine: Fe3Al2(SiO4)3, Pyrope: Mg3Al2(SiO4)3)
Mineral
Chert (specifically White Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Coquina
Bioclastic Limestone (composed primarily of CaCO3)
sedimentary
Pearl
Calcium Carbonate (mostly Aragonite), CaCO3 (with conchiolin)
mineral
Diamond in Kimberlite
Diamond (C in Kimberlite Matrix)
igneous
Rough Diamond
Diamond (pure Carbon, C)
mineral
Diamond
Carbon (C)
mineral
Jadeite Jade
NaAlSi2O6 (Sodium Aluminum Silicate)
metamorphic
Opalite
Synthetic Glass (SiO2 + impurities)
mineral
Aventurine Quartz
Silicon Dioxide (SiO2) with Fuchsite inclusions
metamorphic
Concrete Fragment
Hardened Portland Cement Composite
Anthropogenic (Man-made material mimicking sedimentary rock)
Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Mineral (or mineraloid if microcrystalline)
Granite (Pegmatitic)
Phaneritic Felsic Igneous Rock
igneous
Asphalt (Road Aggregate)
Bituminous Conglomerate / Asphalt Concrete
Anthropogenic (Man-made)
Jadeite (Jade)
Jadeite (NaAlSi2O6)
metamorphic
Fuchsite
K(Al,Cr)2(AlSi3O10)(OH)2 (Chromium-rich Muscovite)
mineral
Obsidian
Obsidian (volcanic glass), predominantly amorphous SiO₂
Igneous
Fuchsite
Chromium-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)
mineral
Fuchsite with Ruby
Cr-rich Muscovite with Corundum (K(Al,Cr)2(AlSi3O10)(OH)2)
metamorphic
Fluorite (Green)
Fluorite (Calcium Fluoride, CaF2)
mineral
Sea Glass
Amorphous Silica (SiO2) with various additives
Mineraloid (Anthropogenic)
Pearl (with Peridot)
Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4
mineral
Prehnite
Prehnite - Ca2Al(AlSi3O10)(OH)2
mineral
Chert (and Jasper/Chalcedony mixture)
Microcrystalline Quartz (SiO2)
sedimentary
Emerald (Tumbled Beryl)
Beryllium Aluminum Silicate (Be3Al2Si6O18) with Chromium/Vanadium impurities
mineral
Green Aventurine
Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2AlSi3O10(OH)2)
metamorphic
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Igneous
Obsidian with Spherulitic Devitrification (Snowflake Obsidian/Mahogany related)
Volcanic Glass (70% or more SiO2)
igneous
Pearl
Aragonite (CaCO3) with Conchiolin
mineral
Granite Cobble/Pebble
Granite
Igneous
Jadeite
NaAlSi2O6 (Sodium Aluminum Silicate)
metamorphic
Chalk
Micrite (primarily Calcium Carbonate, CaCO3)
sedimentary
Rose Quartz Carving
Quartum roseum (Variety of Quartz, SiO2)
Mineral
Diamond (in jewelry setting)
Carbon (C)
mineral
Rough Diamond
Diamond (pure Carbon, C)
mineral
Diamond (or Cubic Zirconia)
Carbon (C) or Zirconium Dioxide (ZrO2)
mineral
Beryl (var. Heliodor or Aquamarine)
Beryllium Aluminum Cyclosilicate (Be3Al2Si6O18)
mineral
Fuchsite
Chromium-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)
mineral
Epidote (or Epidote-rich rock)
Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).
Mineral, often found in metamorphic rocks but also in sedimentary and igneous rocks
Rose Quartz (likely carved)
Rose Quartz (SiO2)
Mineral
Concrete with Aggregate
Composite construction material; primary matrix is Calcium Silicate Hydrate (C-S-H)
anthropogenic (human-made) sedimentary-like material