Haematoxylin
A natural dye from logwood, best known for staining cell nuclei in histology
No single value: Haematoxylin is a material, and its colour varies. The background shows its family, blue.
Haematoxylin is a dye extracted from the heartwood of the logwood tree, used mainly to stain cell nuclei dark blue to black in tissue samples. It has also served as a textile dye and ink, but is now most important in medical and biological staining, especially in the H&E stain for histology.
- Extracted from the heartwood of the logwood tree
- Turns blue to black when oxidized and used with a metal mordant
- Key stain for cell nuclei in medical tissue samples
- Once widely used for dyeing textiles and making ink
- Shortages have led to searches for synthetic alternatives
What colour is Haematoxylin?
Haematoxylin is a dye taken from the heartwood of the logwood tree. In its pure form, it is a colourless, crystalline solid, but commercial samples are usually light to dark brown due to impurities. When used as a stain in biology, it is oxidized to haematein, which produces a strong blue to black colour, especially in cell nuclei. Its main use today is in medical laboratories, where it helps make the structure of tissues visible under the microscope.
Where does Haematoxylin come from?
The name haematoxylin comes from the logwood tree, Haematoxylum campechianum, native to Central America. The dye was first used by the Mayans and Aztecs. Spanish traders brought it to Europe, where it became popular for dyeing textiles and making ink. Its use in science began in the 18th century, with early experiments in staining plant and animal tissues. The most common modern use, staining with haematoxylin and eosin, was first suggested in 1876.
How is Haematoxylin made?
Haematoxylin is extracted from logwood by boiling wood chips or using steam and pressure. The dye can be sold as a liquid or dried into crystals. For staining, haematoxylin is oxidized to haematein, either naturally by air and sunlight or chemically with sodium iodate. The final colour depends on the metal salt, called a mordant, used in the process. Aluminium is the most common mordant, but iron and other metals are also used.
Where Haematoxylin is used
Haematoxylin has coloured textiles, leather, and inks, but is now mainly used in biology and medicine. It stains cell nuclei in tissue samples, making them stand out under a microscope. The H&E stain, which pairs haematoxylin with eosin, is the standard method for examining tissue in hospitals and research. Haematoxylin is also found in the Pap stain for studying cells. In the past, it was important for dyeing wool and cotton, and for making writing and drawing inks.
Blue around the world
What the blue family means from country to country.
The blue band of the flag stands for peace, truth and justice. The exact shade has changed over the years and was fixed as royal blue by law in 1998.
Politics and protestSource: Flag of the PhilippinesLapis lazuli has been mined in the mountains of Badakhshan for more than six thousand years. Ground to powder it gave ultramarine, the costliest blue in European painting.
Royalty and powerSacred and holyAweSource: Lapis lazuliThe chadari is a full-length covering for women with a mesh panel over the eyes. In Kabul and the north it is most often a light blue.
Protection and healingSource: BurqaThe blue band of the flag stands for the wish of the Armenian people to live under peaceful skies. The red above it is for the highlands and the struggle to survive.
Politics and protestHopeSource: Flag of ArmeniaThe flag is sky blue, white and sky blue, created by Manuel Belgrano in 1812. National teams are called the Albiceleste, the white and sky blue.
Politics and protestPrideSource: Flag of ArgentinaBoca Juniors play in blue and gold. The club's story is that in 1907 it took the colours of the flag of the next ship into port, which was Swedish.
Festival and celebrationPrideSource: Boca JuniorsShades and relatives of Haematoxylin
Haematoxylin can produce different colours depending on the mordant and method used, ranging from blue and purple to black. It is sometimes confused with other blue dyes, such as indigo, but the shades and lightfastness differ. Synthetic dyes like celestine blue and gallocyanine have been suggested as substitutes, but none have fully replaced haematoxylin in histology.
Questions people ask about Haematoxylin
What colour is haematoxylin?
In its pure form, haematoxylin is colourless, but when oxidized and used with a mordant, it stains tissues blue to black, especially cell nuclei.
Where does the name haematoxylin come from?
The name comes from the logwood tree, Haematoxylum campechianum, which is native to Central America and is the source of the dye.
What is haematoxylin used for today?
Its main use is in medical and biological laboratories to stain cell nuclei in tissue samples, especially in the H&E stain.
How is haematoxylin made?
It is extracted from logwood by boiling or steaming the wood, then oxidized to haematein for use as a stain.
Has haematoxylin always been used for staining?
No, it was first used as a textile dye and ink. Its use as a biological stain began in the 18th century.
Good reading and sources
- Haematoxylin on WikipediaEncyclopedia
- More pictures on Wikimedia CommonsPictures
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Haematoxylin", 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.
More of the blue family
All of blue
Blue
Lapis lazuli
A deep blue stone prized for jewellery and the source of ultramarine pigmentColour named from nature · 🇦🇫 Afghanistan +5
#6A5DFF
Indigo
A deep blue named for the dye once exported from IndiaNamed shade · 🇮🇳 India +5
Blue
Azurite
A deep blue copper mineral once prized as a pigment and gemstonePigment · 🇫🇷 France +5
Blue
Woad
A blue dye once vital to Europe's textile trade, made from the leaves of a flowering plantDye · 🇫🇷 France +3
Blue
Methylene blue
A synthetic blue dye and medicine first made in 1876Dye
Blue
Indigo
A deep blue dye from plants, now mostly made synthetically and known for colouring denimDye · 🇮🇳 India +5
#120A8F
Ultramarine
A deep blue pigment once made from lapis lazuli, prized for centuries in artPigment · 🇦🇫 Afghanistan +2
#003153
Prussian blue
A deep blue pigment first made in Berlin in the early 1700sPigment · 🇯🇵 Japan
More colours tied to the Philippines
The colours of the Philippines
Yellow
Turmeric
A golden yellow dye and spice from the rhizome of a tropical plantColour named from nature · 🇮🇳 India +5
Red
Realgar
An orange-red arsenic sulfide mineral once used as a pigment and poisonPigment · 🇨🇳 China +5
#800000
Maroon
A deep brownish red named for the French word for chestnutNamed shade · 🇦🇺 Australia +4
Orange
Annatto
A yellow-orange dye and flavour from the seeds of the achiote treeDye · 🇲🇽 Mexico +5