Alizarin Red S
A synthetic red dye used to reveal calcium and minerals in science
No single value: Alizarin Red S is a material, and its colour varies. The background shows its family, red.
Alizarin Red S is a man-made red dye that dissolves in water and is based on alizarin sulfonic acid. First made in 1871, it is mainly used in laboratories to show where calcium is found in tissues or to help tell apart minerals in rocks.
- Discovered by Graebe and Liebermann in 1871
- Turns red to orange when it binds to calcium
- Used to show bone and calcium in lab samples
- Helps geologists tell apart carbonate minerals
- Water-soluble sodium salt of alizarin sulfonic acid
What colour is Alizarin Red S?
Alizarin Red S is a laboratory dye that produces a red to orange colour when it reacts with calcium. It is a sodium salt that dissolves in water, making it easy to use in scientific tests. Its main use is to highlight where calcium or certain minerals are present, which shows up as a bright stain.
Where does Alizarin Red S come from?
This dye was first created by Graebe and Liebermann in 1871. It is a chemical relative of alizarin, a traditional red dye, but has been changed to make it water-soluble and more useful for scientific work. The name comes from its link to alizarin and its red shade.
How is Alizarin Red S made?
Alizarin Red S is made in the laboratory from alizarin sulfonic acid, turning it into a sodium salt. This process makes the dye dissolve in water, which is important for its use in staining tissues and minerals.
Where Alizarin Red S is used
In science, Alizarin Red S is used to show where calcium is found in body tissues, such as bones or deposits. It is also used to mark growth in living corals and to help geologists tell apart carbonate minerals in rock samples. The dye forms a coloured complex with calcium, making these features easy to see.
Red around the world
What the red family means from country to country.
The flag uses the four Pan-Arab colours: a red bar at the hoist with green, white and black bands. It was designed by a young Emirati, Abdullah Al Maainah, in 1971.
Politics and protestPrideSource: Flag of the United Arab EmiratesThe flag is a black double-headed eagle on red, the banner of the fifteenth-century hero Skanderbeg. Fans chant Kuq e Zi, red and black.
Politics and protestPrideSource: Flag of AlbaniaArmenian scribes painted manuscripts with vordan karmir, a crimson dye made from an insect that lives on the roots of grasses in the Ararat plain.
Sacred and holySource: Armenian cochinealUnder Juan Manuel de Rosas in the 1830s and 1840s, everyone had to wear a scarlet ribbon to show loyalty to his Federalist party. His enemies, the Unitarians, were tied to sky blue.
Politics and protestFearSource: Juan Manuel de RosasThe flag is red, white and red. Legend says Duke Leopold V's white tunic was soaked in blood at the siege of Acre, all but the band under his belt.
Politics and protestCourageSource: Flag of AustriaRed ochre is used in Aboriginal rock art and ceremony, and is traded over long distances. In the Aboriginal flag the red half stands for the earth and for that ochre.
Sacred and holyNature and renewalAweSource: Australian Aboriginal flagShades and relatives of Alizarin Red S
Other dyes related to alizarin, such as purpurin, are also used for staining and come from similar chemical families. Alizarin Red S is sometimes called by other names, but its main use is in scientific staining rather than as a general colourant.
Questions people ask about Alizarin Red S
What colour is Alizarin Red S?
Alizarin Red S produces a red to orange colour, especially when it reacts with calcium in tissues or minerals.
Where does the name Alizarin Red S come from?
The name comes from its chemical link to alizarin, a historic red dye, and the 'S' refers to its sulfonic acid form.
What is Alizarin Red S used for?
It is mainly used in science to stain calcium in tissues and to help identify minerals in geology.
Is Alizarin Red S natural or synthetic?
It is a synthetic dye, created in the laboratory rather than from natural sources.
When was Alizarin Red S first made?
It was first made in 1871 by Graebe and Liebermann.
Good reading and sources
- Alizarin Red S on WikipediaEncyclopedia
- More pictures on Wikimedia CommonsPictures
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Alizarin Red S", 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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