Ferruginous Quartzite (also known as Ironstone or Gossan)
Ferruginous Quartzite with Goethite/Hematite staining
metamorphic
Category
Organic (Often Found By Beachcombers)
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Gold Nugget
Native Gold (Au)
mineral
Aluminum Slag
Anthropogenic Aluminum (Al)
mineral
Amethyst (Rough)
Quartz, SiO2
mineral
Jasper (Multi-colored) / Sea Glass Slag
Silicon Dioxide (SiO2) with impurities of Iron Oxide
Sedimentary (if natural Jasper) or Artificial (if Slag)
Basalt with Quartz/Epidote Vein
Mafic volcanic rock (formula primarily (Mg, Fe)2SiO4 and CaAl2Si2O8)
igneous
Amber and Citrine Quartz
Succinite (Amber) and Silicon Dioxide (SiO2 / Citrine)
mineral
Siderite Concretion in Shale
Iron carbonate (FeCO3) in Mudstone/Shale matrix
sedimentary
Amber
Resinite / Fossilized Tree Resin
mineral
Kidney Stone
Nephrolithiasis (Calcium Oxalate, Hydroxyapatite, or Uric Acid)
mineral
Ironstone concretion / Limonitic Sandstone
Goethite/Hematite Cemented Sandstone (Hydrated Iron Oxide)
sedimentary
Chert (Agatized/Chalcedony variety)
Microcrystalline Quartz (SiO2)
sedimentary
Amber
Succinite (C10H16O)
mineraloid
Chert (Jasper/Chalcedony mix)
Microcrystalline Quartz (SiO2)
sedimentary
Horse Chestnut (Buckeye seed)
Aesculus hippocastanum seed
Organic (Non-geological)
Kidney Stone
Calcium Oxalate (CaC2O4), Uric Acid, or Struvite
mineral
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
mineral
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Amber
Succinates (Fossilized Tree Resin)
mineraloid
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
sedimentary
Fossiliferous Limestone
Fossiliferous Limestone
sedimentary
Mother of Pearl (Nacre)
Aragonite (CaCO3) with Organic Matrix
mineral
Limestone (specifically Bituminous or Carbonaceous Limestone)
Calcium Carbonate (CaCO3) with Organic Impurities
sedimentary
Chert (often called Flint when found in chalk)
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon dioxide (SiO2)
sedimentary
Naga Silver-Inlaid Ebony and Bone/Horn Beads
Diospyros (Ebony) or Keratin (Horn) with Silver/White-Metal Inlay
Organic (Anthropological Artifact)
Amber
Succinite (Formula: C10H16O)
Mineraloid
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Pyritic Shale
Carbonaceous Shale with Iron Pyrite (FeS2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Coarse Sand or Fine Gravel
Detrital Sedimentary Fragments (mostly SiO2)
sedimentary
Manganese Dendrite on Siltstone
Manganese Oxide (pyrolusite or psilomelane) Dendrites
mineral/sedimentary
Amber
Succinite (fossilized tree resin), C10H16O
Organic Gemstone
Amber
Succinite (Organic Gemstone)
mineral
Shale with Pyrite
Clastic sedimentary rock containing Iron Disulfide (FeS2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Fossil Shark Tooth
Carcharodon sp. (likely Otodus or similar Lamniformes order)
sedimentary
Chert (Green and Black Jasper variant)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Green Chert
Microcrystalline Quartz (SiO2)
sedimentary