Cuprite
A minor copper ore known for its deep red color.
Cuprite is an oxide mineral composed of copper(I) oxide (Cu2O) and serves as a minor ore of copper. It is known for its dark crystals with red internal reflections and is sometimes called ruby copper due to its distinctive red color.
- composition
- Copper(I) oxide (Cu2O)
- crystal_system
- Isometric hexoctahedral class
- mohs_hardness
- 3.5 to 4
- specific_gravity
- 6.1
- luster
- Sub-metallic to brilliant adamantine
- name_origin
- Latin cuprum for copper
Lore & Background
Cuprite forms as a secondary mineral in the oxidized zone of copper sulfide deposits, frequently occurring with native copper, azurite, chrysocolla, malachite, tenorite, and iron oxide minerals. Its crystals appear as cubic, octahedral, or dodecahedral forms, often with penetration twins. The variety chalcotrichite shows elongated capillary or needle-like crystals.
Reader's Guide
Cuprite is significant as a minor ore of copper and as a collector's gemstone. Although most crystals are too small for faceting, a unique deposit from Onganja in Seeis, Namibia, discovered in the 1970s, produced large gem-quality crystals. Virtually every faceted stone over one carat comes from this now-depleted deposit. Faceted cuprite is considered highly collectible due to its deep garnet coloring and brilliance exceeding that of diamond, though its softness (Mohs 3.5–4) prevents it from being widely used in jewelry.
Did You Know?
- Cuprite has a relatively high specific gravity of 6.1.
- The variety chalcotrichite means 'plush copper ore' in Ancient Greek.
- Cuprite is known as ruby copper due to its distinctive red color.
- Almost all faceted cuprite over one carat comes from a single deposit in Namibia discovered in the 1970s.
Frequently Asked Questions
Who is Cuprite?
Cuprite is a copper(I) oxide mineral (Cu₂O) that appears as dark crystals showing striking red internal reflections. It is a minor copper ore and is sometimes nicknamed "ruby copper" for its rich red hue.
What are Cuprite's key physical traits?
It crystallizes in the isometric hexoctahedral class, sits at a Mohs hardness of 3.5 to 4, and has a specific gravity of 6.1. Its luster ranges from sub-metallic to a brilliant adamantine shine.
Why does Cuprite matter to collectors and industry?
As a minor ore of copper, it plays a supporting role in copper extraction. Its distinctive deep-red color and adamantine sparkle also make it a sought-after specimen among mineral collectors.
How is Cuprite different from other copper minerals?
Its defining feature is the deep red internal reflection combined with a sub-metallic to adamantine luster, which sets it apart from the more common blue-green copper minerals like malachite or azurite.
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