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pigment of the month

green earths
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Celadonite claystone hill at John Day Oregon

Sheep Rock Unit at John Day Monument in eastern Oregon state, entire hills are tinted green. Only two percent celadonite is necessary to produce this much coloration in the natural claystones found here. 

Green earths and other green-producing minerals have most likely been employed since the beginning of time however, finding proof of the use of a pigment in the deep past is difficult due to a number of conditions that eradicate them from the naked eye. Exposure to the elements, human interference, deterioration of the substrate, and more, are effective at making pigments invisible. While many objects could be tested for evidence of mineral pigments, few people are yet doing that kind of testing which is leaving a huge gap in our information about pigment use. So, people like me have to wait to for someone to unearth objects that do have visible pigments on them. like the Coast Salish celadonite (NWC people had a grinding stone, paint dish and brushes for each color so they didn't contaminate their colors) grinding stone found at the 4,000 year level of a Coast Salish midden on a small island off the coast of British Columbia, Canada.

 

 

 

 

 

While the grinding stone came out of the 4,000 yr level, it may be much older, but we at least have a date to work from of approximately 2,000 years BCE. While researching celadonite use by Northwest Coast Indigenous people, and expanding that research to the entire globe and throughout history, I have been able to determine the use of celadonite as a pigment by the Coast Salish people is the earliest known use in the world, predating even Roman use by more than a thousand years.  

While this speaks to the long history of terra vertes as paint pigments, lately we've seen "new" green pigments (see the gallery below) hit the market, but little is known of their historical use. Of course we have good records of the use of malachite, but what about the more than two dozen other green mineral pigments? I have no doubt that they've all been experimented with by artists throughout history, but the documentation on them is so rare that we don't really know anything about them yet. 

4,000 year old Coast Salish pigment grinding stone with celadonite pigment

List of minerals that produce green pigments

 

Actinolite: Ca₂Si₈O₂₂(OH)₂

Aerigine: NaFe3+[Si2O6]

Amazonite: KAlSi3O8

Atacamite: Cu2Cl(OH)3

Celadonite: K(MgFe3+◻)(Si4O10)(OH)2

Chlorite: (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6

Chromite: FeCr2O4

Chrysocolla: Cu₂H₂Si₂O₅(OH)₄

Diopside: MgCaSi2O6

Dioptase: Cu6Si6O18·6H2O

Epidote: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)

Eskolaite: Cr2O3

Fuschite: K(Al,Cr)2(AlSi3O10)(OH)2

Glauconite: (Fe3+,Mg,Al)2(Si,Al)4O10](OH)2

Green apatite: Ca5(PO4)3(F,Cl,OH)

Green Jasper: SiO₂

Jadeite: NaAlSi2O6

Mariposite: K(Al,Cr)2(Al,Si)4O10(OH)2

Nephrite: Ca₂(Mg,Fe)₅Si₈O₂₂ (OH)₂

Olivine: (Mg, Fe)₂SiO₄

Prehnite: Ca2Al(AlSi3O10)(OH)2

Serpentine: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)

Uvarovite: Ca3Cr2Si3O12

Variscite: AlPO4·2H2O

Volkonskoite: Ca0.3(Cr,Mg,Fe)2((Si,Al)4O10)(OH)2 · 4H2O

Zoisite: (CaCa)(AlAlAl)O[Si2O7][SiO

But, that's part of what excites many of us who work with pigments: exploring and experimenting with new materials. Playing with some epidote recently I discovered that it not only granulates beautifully, it also settles out on my watercolor paper displaying different shades of greens, golds and browns that add texture and depth to a painting. There's no way I could replicate that effect on my own and I am delighted the pigment does it naturally. 

Then there's serpentine which I love because it produces a beautiful yellowish green that is great on it's own for bringing highlights into a work, and it mixes well with other colors to produce an incredible range of greens that make landscapes and botanical paintings come to life. 

I've used chrome green as well as chlorite for many years; I especially like chlorite for it's subtlety and how well it works for painting lichens and softer landscapes. Chrome green (also known as chromium oxide green) is strong and is useful for shadows and adding depth. 

There are so many green mineral pigments there's not time to go into each here, but the list to the right presents fun and interesting opportunities for experimenting with these gorgeous pigments! 

We'd love to hear your experiences with some of the ones on the list. You can share your thoughts in the comment section below, in the forum or email us.

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