Howlite
Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)
Category
Browse sedimentary (anthropogenic) specimens identified by the Rock Identifier community.
Howlite
Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)
Marble
Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)
Celestine (Celestite)
Strontium sulfate (SrSO4)
Hematite
Iron(III) oxide (Fe2O3)
Chert (specifically Flint or Jasper variant)
Microcrystalline Quartz (SiO2)
Gold
Native Gold (Au)
Magnetite (Iron Ore)
Magnetite (Fe3O4)
Limonite with Iron Inclusions
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Chert (often called Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Hag Stone
Perforated Sandstone (composed of SiO2 and calcareous cement)
Slate with Red Sandstone Landscaping Rock
Foliated Pelitic Metamorphic Rock (Slate) and Ferruginous Sandstone
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Quartz (Druzy Quartz)
Silicon Dioxide (SiO2)
Yellow Quartzite River Cobble
Meta-quartzite (SiO2 with iron oxide staining)
Granite (Dioritic or Hornblende-rich)
Phaneritic Plutonic Felsic to Intermediate Igneous Rock
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Quartz (Milky/Iron-stained)
Silicon Dioxide (SiO2)
Orange Quartzite (River Pebble)
Quartzite (primarily SiO2)
Yellow Quartz Pebble (Citrine or Iron-stained Quartz)
Silicon Dioxide (SiO2)
Honey Calcite Geode Segment
Calcite (Calcium Carbonate, CaCO3)
Fossilized Sea Urchin (Echinoid)
Echinoidea (Class); commonly Clypeasteroida for sand dollar types
Limonite (often after Hematite or Goethite)
Limonite (FeO(OH)·nH2O)
Limonite (with Goethite/Ironstone)
FeO(OH)·nH2O (Hydrated Iron Oxide)
Druzy Quartz on Host Rock
Silicon Dioxide (SiO2)
Grey Slate
Foliated Metamorphic Rock (formed by low-grade regional metamorphism of shale or mudstone)
Dalmatian Stone
Peralkaline Feldsphathic Igneous Rock
Jasper (brecciated or orbicular variety)
Silicon dioxide (SiO2) with iron oxide inclusions
Chert (or Flint)
Chert (cryptocrystalline quartz), SiO2
Black Opal
Hydrated Silica (SiO2·nH2O)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated Iron Oxide)
Petrified Wood
Silicified Wood (primarily SiO2)
Puddingstone
Conglomerate (specifically a type of jasper conglomerate or quartz conglomerate)
Leopardskin Jasper
Jasper (a variety of microcrystalline Quartz)
River Stone / Pebble
Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)
Magnetite
Magnetite (Fe3O4)
Quartz (likely) or a Quartzite Pebble
Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.
Celestine (or Celestite) Geode
Strontium Sulfate (SrSO4)
Quartz (Clear Quartz)
Silicon Dioxide (SiO2)
Chert (Tan/Grey variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Pyrite
Iron Sulfide (FeS2)
Clear Quartz (Rock Crystal)
Quartz (Silicon Dioxide, SiO2)
Chert (Field-collected Arrowhead-shaped Fragment)
Microcrystalline or Cryptocrystalline Quartz (SiO2)