Quartz

Quartz is a major silicate mineral that consists of a series of silicon-oxygen tetrahedra in which each oxygen atom is shared, resulting in the chemical formula SiO2. It is the second most abundant mineral in Earth’s continental crust and it is relatively hard (Slavic ancestors of the German word quarz translate to “hard” in English). Quartz is often colorless but there are many different varieties in different colors, including semi-precious gemstones such as amethyst, citrine and chalcedony.


Information source: Mindat.org

Image: Quartz crystals found in the USA. Credit: Parent Géry, Wikimedia Commons.

Diamond

Diamond is a gemstone that consists entirely of carbon (C). It is typically colorless and is the hardest natural mineral on Earth because of its very dense crystal structure (the Greek word adamas translates to ‘unbreakable’ in English). It is formed at high temperatures and pressures in the mantle and as a result it is metastable at Earth’s surface. Diamond is a precious stone commonly used in jewelry, together with sapphire, ruby and emerald.


Information source: Mindat.org

Image: White diamond crystal found in South Africa. Source: Parent Géry, Wikimedia Commons.

Emerald

Emerald is a gemstone variety of the mineral beryl (Be3Al2(SiO3)6). It generally has a green color (the Greek word smaragdos translates to ‘green gem’ in English), which is related to the presences of trace amounts of chromium or vanadium in the mineral structure. Emerald is a precious stone commonly used in jewelry, together with sapphire, ruby and diamond.


Information source: Mindat.org

Image: Emerald crystals found in Colombia. Source: Parent Géry, Wikimedia Commons.

Ruby

Ruby is a gemstone variety of the aluminum oxide mineral corundum (Al2O3). The red color from which its name is derived (the Latin word ruber translates to ‘red’ in English) is related to the presence of trace amounts of chromium in the mineral structure. Ruby is a precious stone commonly used in jewelry, together with sapphire, emerald and diamond.


Information source: Mindat.org

Image: Ruby crystals found in Vietnam. Source: Parent Géry, Wikimedia Commons.

Sapphire

Sapphire is a gemstone variety of the aluminum oxide mineral corundum (Al2O3). It often has a blue color (the Greek word sappheiros translates to ‘blue stone’ in English), which is the result of the incorporation of trace amounts of iron in the mineral structure. Sapphire is a precious stone commonly used in jewelry, together with ruby, emerald and diamond.


Information source: Mindat.org

Image: Sapphire crystals found in Pakistan. Source: Parent Géry, Wikimedia Commons.