Every specimen is a record of how it formed. The flash in labradorite, the cubes of fluorite, and the blades of kyanite each come from a specific structure and a specific set of conditions inside the Earth. These guides explain what you are looking at, in plain language, with sources.
Browse current specimens at Digital Towns Market
Start with a mineral
- Labradorite: why it flashes, and why the flash moves when you tilt it.
- Fluorite: why it grows in cubes, and how it gave fluorescence its name.
- Kyanite: the mineral with two hardness values.
- Pegmatite: how it grows giant crystals, and why slow cooling is not the whole story.
- Apophyllite: the crystals that grew inside ancient lava flows in India.
More guides are on the way: stilbite, calcite, rose quartz, and carnelian.
Mineral, crystal, rock: the short version
A mineral is a naturally occurring solid with a defined chemical composition and an ordered internal structure. Quartz, fluorite, and kyanite are minerals.
A crystal is a single piece of a mineral whose outer shape reflects that internal order. Flat faces and repeating angles are the visible result of atoms stacking in a regular pattern.
A rock is a mixture of minerals. Pegmatite, for example, is a rock made mostly of quartz, feldspar, and mica.
Natural forms and shaped pieces
Some specimens are sold the way they grew. Others are cut and polished from rough material. Both are real mineral. They are simply different objects.
- Clusters, raw pieces, and cabinet specimens keep their natural crystal faces and often their host rock, called matrix.
- Towers, spheres, cubes, pyramids, hearts, and freeforms are shaped and polished by hand or machine. The shape is craft. The material is natural.
Knowing which one you are buying helps you judge it fairly. A natural cluster is valued for its crystal form and condition. A polished piece is valued for its material, color, and finish.
How to read a specimen listing
- Weight and dimensions. Photos hide scale. The measurements tell you what will arrive.
- One of one, or one of several. Many listings show the exact piece. Where a listing covers several similar pieces, it says so.
- Locality. Where a specimen was found is part of its identity. It is named when it is documented.
- Photographs. Look for more than one angle, especially for stones with optical effects that change with the light.
Browse current specimens
Towers, spheres, clusters, raw pieces, and cabinet specimens are all in the Crystals & Minerals category at Digital Towns Market.
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