A very smart, visual and educational image by geologist and artist Lina Jakaitė-Darkšė to communicate the chemistry of the most relevant garnet species for gemmologists (those with known gem varieties).
In this image we can see the relationships between end-members of the pyralspite and ugrandite isomorphic series of the so-called garnet group by mineralogists, being members of the larger and much complex garnet supergroup of minerals that includes many mineral species besides these known silicates.
Please note that the six mineral species represented here are the approved IMA (International Mineralogical Associations) designations and that the colours here in this artwork are merely representative for the sake of easy communication.
Gem garnets have been referred to in the trade by a vast number of varietal names and trade names that are usually related to colour, colour phenomena or mining locality.
Chemically, these are typically solid solutions between these end-member compositions, roughly meaning that they have intermediate-variable compositions. For example, one can hardly get a pure almandine or pure pyrope red garnet. Those reddish varieties typically have an almandine (iron) and pyrope (magnesium) content, often also with spessartine (manganese) content. These varying terms contribute strongly to the garnet’s colour and major properties.
Guest articles by Rui Galopim de Carvalho:
https://gem-spectrum.com/category/rui-galopim-de-carvalho
About the author:
Rui Galopim de Carvalho is a renowned independent Gem Education Consultant, author, luxury industry training expert and popular international lecturer on gemmology and on the history of gem materials. During his 30 year experience as a gemmologist, Rui has studied important collections in both public and private museums, notably the Portuguese Crown Jewels.
Founder of the popular Home Gemmology webinar series launched during the COVID-19 lockdown, Rui has a long history as a gemmology communicator, notably on social media where he is a popular figure.
He is associate editor of Gem-A’s Journal of Gemmology, Vice-President of the Coral Commission of The World Jewellery Confederation – CIBJO, member of the Communications Committee of ICA (International Colored Gemstone Association), ambassador for LAUREL -Portuguese Association of Excellence Brands (ECCIA member) and consultant for several private collections and trade organizations.
Rui Galopim de Carvalho can be reached through his website:
