Glauconite
A soft green mineral used as a pigment and in fertilisers
No single value: Glauconite is a material, and its colour varies. The background shows its family, green.
Glauconite is a green mineral in the mica group, found as small rounded grains in marine sands and rocks. Its name comes from the Greek for 'bluish green', and it is known for its use as a pigment called green earth in painting and as a source of potassium in fertilisers.
- Glauconite is a main source of the pigment green earth.
- It forms in marine environments with slow sediment build-up.
- Used as a potassium-rich fertiliser in agriculture.
- Colour ranges from olive green to bluish green.
- Soft and easily crumbles, with low weathering resistance.
What colour is Glauconite?
Glauconite is a mineral with a green colour that ranges from olive and bluish green to yellowish tones when exposed to air. It is usually found as small, rounded grains, about the size of sand, and is soft enough to crumble easily. Its green shades and earthy look set it apart from other minerals, and it can sometimes be mistaken for chlorite or clay minerals.
Where does Glauconite come from?
The name 'glauconite' comes from the Greek word 'glaucos', which means 'bluish green', describing its typical colour. It forms in marine environments, especially on continental shelves where sediment builds up slowly. Glauconite has been recognised since at least the 19th century, and its green sands were first widely described by scientists on the HMS Challenger expedition.
How is Glauconite made?
Glauconite forms naturally in marine settings, often as a result of chemical changes in sediments rich in iron-bearing micas. It develops in low-oxygen conditions, sometimes helped by the decay of organic matter in animal shells. The mineral is found in greensand, siltstone, and sandstone, and is not made synthetically.
Where Glauconite is used
Artists have used glauconite as a pigment called green earth, especially in oil painting and wall painting. It was used for underpainting skin in medieval art and appears in Russian icon paintings and Roman wall paintings. Glauconite is also important in agriculture, where it is used as a source of potassium in fertilisers and to adjust soil pH.
Green around the world
What the green family means from country to country.
The green field of the flag is commonly said to stand for the forests. It was first the colour of the House of Braganza, the family of the first emperor.
Politics and protestNature and renewalPrideSource: Flag of BrazilA green kerchief is the sign of the campaign for legal abortion. Huge crowds wore it in 2018, and the movement was called the green wave.
Politics and protestHopeSource: Green scarfGreen and gold have been the official national colours since 1984 and are worn by national sports teams. They echo the leaves and flowers of the golden wattle.
Festival and celebrationPrideSource: National colours of AustraliaA Test cricketer is given a dark green cap, the baggy green, on first playing for Australia. Many players wear the same faded cap for a whole career.
Festival and celebrationPrideSource: Baggy greenThe green field of the flag stands for the land and its rice fields. Many people also read it as the youth and vigour of the country.
Nature and renewalPolitics and protestHopeSource: Flag of BangladeshThe flag is white, green and red. The green band, which took the place of the blue in the Russian flag, is read as the country's forests and farmland.
Politics and protestNature and renewalSource: Flag of BulgariaShades and relatives of Glauconite
Glauconite's colour can vary from olive green to bluish green and may turn yellowish when it oxidises. It is sometimes confused with chlorite, another green mineral, or with certain clay minerals. Greensand refers to rocks rich in glauconite, but may also include other minerals.
Questions people ask about Glauconite
What colour is glauconite?
Glauconite is typically green, ranging from olive and bluish green to yellowish green when exposed to air.
Where does the name glauconite come from?
The name comes from the Greek word 'glaucos', meaning 'bluish green', describing its usual colour.
What is glauconite used for?
It is used as a pigment in painting (called green earth) and as a source of potassium in fertilisers.
Where is glauconite found?
Glauconite forms in marine environments, especially in sands and rocks on continental shelves. Notable deposits are in Brazil and Canada.
Is glauconite the same as greensand?
Greensand is a rock or sediment rich in glauconite, but may also contain other minerals.
Good reading and sources
- Glauconite on WikipediaEncyclopedia
- More pictures on Wikimedia CommonsPictures
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Glauconite", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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