Mineraloid

Granite

Granite (Phaneritic igneous rock)

Granite

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

Gneiss

Gneiss (a type of metamorphic rock)

Drill Core Sample

Cylindrical Rock Core (Specific mineralogy varies by extraction site)

Pyrite Sun (Pyrite Dollar)

Iron Disulfide (FeS2)

Banded River Rock / Gneiss (highly weathered)

Gneiss

Granite

Intrusive Phaneritic Felsic Igneous Rock

Schist

Schist (various mineralogical compositions including mica, chlorite, talc, etc.)

Pegmatite (likely Granitic Pegmatite)

Pegmatite (a coarse-grained igneous rock, often with granitic composition)

Sandstone Concretion

Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)

Diorite

Diorite (an intermediate intrusive igneous rock)

Prasiolite and Quartz Crystal Cluster

Quartz (SiO2); Prasiolite is a variety of Quartz

Brick

Fired clay or Ceramic material (no specific mineralogical scientific name as it's a composite)

Eclogite

Eclogite (Omphacite + Almandine-Pyrope Garnet)

Limonite (Ironstone Concretion)

Limonite (Hydrous Ferric Oxides mixed with Goethite)

Pink Granite

Phaneritic Felsic Igneous Rock

Gabbro

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

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions

Charoite

Charoite (K(Ca,Na)2Si4O10(OH,F)·nH2O)

Sandstone

Quartz Arenite (a common type of sandstone, given the appearance), Arkose, Greywacke (depending on mineralogy)

Tiger's Eye (with Hematite/Jasper)

SiO2 (Silicon Dioxide) with Fe2O3 (Hematite)

Greisen

Greisen

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Hypersthene

(Mg,Fe)SiO3 - Enstatite-Ferrosilite series

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Banded Gneiss

Gneiss (pronounced 'nice')

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Sugilite

Sugilite (KNa2(Fe,Mn,Al)2Li3Si12O30)

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Pearl (likely Freshwater or Akoya Cultured)

Aragonite / Conchiolin composite (CaCO3)

Granite (likely a river or beach pebble)

Granite (a felsic intrusive igneous rock primarily composed of quartz, feldspar, and mica)

Hypersthene (or Enstatite/Ferrosilite)

Orthopyroxene series (Mg,Fe)SiO3 - specifically, historically hypersthene (intermediate member) now referred to as Enstatite (Mg-rich) or Ferrosilite (Fe-rich)

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.