Mineralogical Specimen

Pale-green schist fragment

Chlorite–sericite schist, possibly containing epidote or actinolite

Flint or chert flake

Microcrystalline quartz (SiO₂), commonly chert/flint

Iron-rich metamorphic rock, likely specular hematite-bearing schist

Hematite–quartz–mica schist (tentative)

Limonite (Ironstone Concretion)

Limonite (Hydrous Ferric Oxides mixed with Goethite)

Granite

Intrusive Igneous Rock

Granite

Intrusive Igneous Rock

Tiny rounded brown mineral grain

Indeterminate; possibly iron oxide, garnet, or a weathered sulfide grain

Rounded river pebble (likely weathered granite or metamorphic rock)

Indeterminate; possible granitic or quartz-rich lithology

Granite

Phaneritic Igneous Rock (composed primarily of Quartz SiO2, Alkali Feldspar, and Plagioclase)

Eclogite

Eclogite (Omphacite-Garnet rock)

Granite

Phaneritic Felsic Igneous Rock

Granite

Phaneritic Felsic Igneous Rock

Granite

Phaneritic Felsic Igneous Rock

Optical Calcite (Iceland Spar)

Calcite (Calcium Carbonate, CaCO3)

Likely gabbro or basaltic rock fragments

Mafic igneous rock, chiefly plagioclase feldspar and pyroxene; exact identification requires testing

Granite

Intrusive igneous rock

Chert or flint nodule

Microcrystalline quartz (SiO₂), commonly chalcedony with possible opaline silica

Weathered quartz-rich pebble

Likely granitic or feldspathic clast; chiefly quartz (SiO₂) and feldspar

Flint or chert

Microcrystalline quartz (SiO₂), likely gray chert/flint

Black volcanic rock, likely basalt

Basalt; primarily plagioclase feldspar and pyroxene, commonly with minor olivine or magnetite

Diorite Gneiss

Foliated Diorite Gneiss

Likely basalt or dark mafic rock fragment

Basalt; primarily plagioclase feldspar and pyroxene, commonly with olivine and iron oxides

Weathered iron-rich rock, likely magnetite-bearing basalt or ironstone

Basalt/ironstone mixture dominated by iron oxides, chiefly magnetite (Fe3O4) and hematite (Fe2O3)

Yellow-green aventurine or serpentine pendant

Most likely serpentine-group mineral (magnesium silicate), possibly quartz-rich aventurine

Weathered porphyritic volcanic rock

Likely andesite or dacite, with feldspar phenocrysts in a fine-grained groundmass

Weathered iron-rich rock, possibly limonite-bearing basalt or ironstone

Undetermined; likely iron oxides/hydroxides (goethite–hematite–limonite) in a silicate host

Rhyolite (possibly porphyritic and altered)

Volcanic felsic rock; primarily quartz, alkali feldspar, plagioclase, and volcanic glass, with iron-oxide alteration

Banded Calcite (Mexican Onyx)

Calcium Carbonate (CaCO3)

Dragon Blood Jasper

Quartz (SiO2) with Epidote and Piedmontite inclusions

Tumbled goldstone-like quartz pebble

Likely iron-stained quartz or jasper; exact identification requires testing

Dragon Blood Jasper

Microcrystalline Quartz (Chalcedony) with Epidote and Piemontite

Amygdaloidal basalt pebble

Vesicular basalt, locally calcite- or quartz-filled amygdales

Dark mafic rock, likely basalt

Basalt; primarily plagioclase feldspar and pyroxene, commonly with olivine and iron oxides

Weathered river pebble, likely quartz-rich sandstone or quartzite

Indeterminate; probable quartz (SiO₂)-rich sandstone/quartzite with iron-oxide staining

Banded slate or phyllite

Fine-grained foliated metasedimentary rock; likely slate with light-colored quartz veins

Weathered iron-rich sandstone or ironstone cobble

Ferruginous sandstone/ironstone, chiefly quartz (SiO₂) cemented or stained by iron oxides and hydroxides

Jasper and Greenstone Pebble

Siliceous rock / Metamorphic pebble

Quartz-bearing dark mineral specimen

Quartz (SiO₂) on a dark host rock, possibly basalt or sulfide-rich ore

Green Obsidian Sphere (man-made glass)

Vitreous Silica with Chromium/Iron additives

Rounded iron-rich pebble

Likely ferruginous sandstone or ironstone; exact identification requires testing

Gabbro

Gabbro (composed mainly of calcium-rich plagioclase feldspar and pyroxene)

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions