Metamorphic Or Igneous Alteration

Browse metamorphic or igneous alteration specimens identified by the Rock Identifier community.

Peridot and Citrine Gemstones (in a ring setting)

Peridot (Olivine: (Mg,Fe)2SiO4), Citrine (Quartz: SiO2)

mineral

Quartz

Silicon Dioxide (SiO2)

Mineral

Amethyst Quartz

SiO2 (Silicon Dioxide)

Mineral

Fluorite and Rose Quartz

Fluorite (CaF2), Rose Quartz (SiO2)

Mineral

Garnet (likely Pyrope or Almandine)

Garnet Group (complex nesosilicate minerals, e.g., Pyrope Mg3Al2(SiO4)3, Almandine Fe3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3, Grossular Ca3Al2(SiO4)3, Andradite Ca3Fe2(SiO4)3, Uvarovite Ca3Cr2(SiO4)3). The vivid red color in the image strongly suggests Pyrope or Almandine.

Mineral

Rose Quartz

Rose Quartz (SiO₂)

mineral

Calcite (commonly referred to as Orange Calcite or Honey Calcite given its color)

Calcite

Mineral

Green Aventurine

Aventurine (a variety of Quartz, SiO2)

Mineral

Quartz (possibly milky quartz or quartz with inclusions)

SiO2 (Silicon Dioxide)

Mineral

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Red Jasper (Opaque Chalcedony)

Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions

mineral

Quartz

Quartz (SiO2 - Silicon Dioxide)

Mineral, often found as detrital grains in sedimentary rocks

Bronzite

MgSiO3 (Enstatite with 10-30% FeSiO3 in solid solution)

Mineral

Quartz

Silicon Dioxide (SiO₂)

Mineral

Quartz Geode/Cluster

Quartz (SiO2)

mineral

Drill Core Samples (Varied Lithology)

Multi-lithological core samples (containing potential granite, marble, and phyllite/schist sequence)

igneous, sedimentary, and metamorphic

Quartz (on matrix)

Quartz (Silicon Dioxide, SiO₂)

Mineral

Orthoclase Feldspar (or K-Feldspar)

Orthoclase (KAlSi3O8)

Mineral

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Metamorphic or Igneous (context dependent)

Calcite

Calcite (CaCO₃)

Mineral

Mica (specimen appears to be Muscovite or Phlogopite)

Phyllosilicate mineral; Muscovite: KAl2(AlSi3O10)(F,OH)2

Mineral (Found in Igneous and Metamorphic rocks)

Quartz (likely macrocrystalline variety)

Quartz (SiO₂)

Mineral

Quartz (likely Yellow/Orange variety, possibly Citrine or Chalcedony with iron staining)

Quartz (SiO₂)

Mineral

Quartz (milky quartz variety)

Quartz (SiO₂)

Mineral

Sunstone

Plagioclase Feldspar (specifically Oligoclase variety containing hematite or goethite inclusions)", composition: (Ca,Na)(Al,Si)2Si2O8

Mineral

Smoky Quartz

SiO2 (Silicon Dioxide)

mineral

Aventurine (Green Aventurine)

Quartz with Fuchsite Inclusions (SiO2)

Mineral

Smoky Quartz

SiO2 (Silicon Dioxide)

Mineral

Pyrite

Pyrite (FeS2)

Mineral

Quartz (likely milky quartz or a stained variety)

Silicon Dioxide (SiO₂)

Mineral

Mixed Tumbled Gemstones and River Rocks

Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)

Mixed (Igneous, Sedimentary, Metamorphic, and Minerals)

Quartz / Quartzite Fragment

Silicon Dioxide (SiO2)

igneous, sedimentary, or metamorphic (mineral-based)

Calcite

Calcite (CaCO3)

Mineral

Green Aventurine

Aventurine (a variety of Quartz, SiO2)

Mineral

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix

igneous

Serpentinite

Serpentinite (composed primarily of serpentine-group minerals like antigorite, chrysotile, and lizardite; chemical formula varies but generally Mg3Si2O5(OH)4)

Metamorphic Rock