Totally Cube-ular

From fool's gold to a commonly used food seasoning, explore the cubic minerals in the MGMH collection

By Mineralogical and Geological Museum, Harvard University

Cube Molecules (2024-04-30) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Cubic minerals

The cubic crystal system is one of the most simple and common classes of crystals. Cubic minerals have straight edges and sharp corners which gives them a blocky appearance.

Some examples of cubic minerals are pyrite, halite, galena, fluorite, and diamond.

Blue Fluorite (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Fluorite

Fluorite commonly forms through hydrothermal activity when calcium and fluorine in fluids react to form crystals. The chemical composition of fluorite is CaF2.

Purple Fluorite (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Fluorite is a major source of fluorine

It is also used as a flux in steel manufacturing and for the production of hydrofluoric acid.

Diamond cube (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Diamond

Diamonds are composed of only one element, carbon. Diamonds form under intense heat and pressure when carbon atoms are squeezed together.

17 Diamond cubes (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Diamonds are most commonly used in jewelry

They are also effective for cutting and drilling.

3 Pyrite cubes (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Pyrite

Pyrite is commonly known as fool’s gold. Pyrite is a common mineral in many types of rock and also forms in hydrothermal veins. The chemical composition of pyrite is FeS2.

Pyrite (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Pyrite is used for the production of sulfuric acid

It is also mined for its common association with gold and copper.

Pyrite Cubes Stacked (2024-04-30) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Pyrite can have “pyrite disease”

When pyrite is exposed to humid air, it can oxidize and release corrosive acid and gas that can destroy the specimen.

Halite (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Halite

Halite forms when seawater or salty lake water evaporates and leaves behind salt deposits. The chemical composition of halite is NaCl.

Blue Halite (2024-04-30) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Halite is commonly used for food seasoning (table salt!)

It is also used for food preservation and road ice management.

Galena 1 (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Galena

Galena can be found in hydrothermal veins. The chemical composition of galena is PbS.

Galena 2 (2024-04-30) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Galena is an important lead ore

It is also mined for its silver content. The lead from galena is used to make batteries, lead sheets, and lead pipes.

Diamond cubes smiley face (2024-04-23) by Rachel GnieskiMineralogical and Geological Museum, Harvard University

Cool cubes!

Cubic minerals not only look cool, but also have common uses in everyday life.

Credits: Story

Story by Gillian Garcia
Photos by Rachel Gnieski and Christina Byrd

Credits: All media

The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.

Mineralogical and Geological Museum, Harvard University

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