Minerals are the naturally occurring building blocks of rocks — each with a characteristic chemical composition and an orderly crystal structure. They are identified by properties such as hardness (see the Mohs Hardness Scale), color, luster, streak, and crystal form.
A few specimens from the collection
A couple of these are technically mineraloids rather than true minerals — amber is fossilized resin and obsidian is volcanic glass — but they are collector favorites all the same.
Agate is a banded form of chalcedony (microcrystalline quartz), prized for its colorful concentric layers. Condor agate, like this belt-buckle stone, comes from Argentina.
Snowflake obsidian is volcanic glass speckled with pale “snowflakes” — small clusters of the mineral cristobalite that crystallized within the glass.
From Bosco’s collection
A few mineral specimens Bosco has collected or acquired over the years (shown with a scale rule).
Rocks
Rocks are aggregates of one or more minerals, and each one records how and where it formed. The specimens below are an eclectic mix — some earthly, a couple from beyond it.
Lapis lazuli is a deep-blue metamorphic rock colored by the mineral lazurite and often flecked with golden pyrite. Prized since antiquity, it was once ground into the precious pigment ultramarine.
Meteorite — a piece of rock or metal from space that survived the fiery plunge to Earth. Most are fragments of asteroids, older than any rock that formed on our own planet.
Rhodonite is a rose-pink manganese silicate, usually laced with black veins of manganese oxide — a favorite for carving and cabochons.
Tektite — natural glass forged when a meteorite impact melts terrestrial rock and flings it skyward, where it cools in mid-flight into dark, often sculpted shapes.