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khroma is a utility package: it provides usefull colour schemes for archaeological data visualization. khroma provides Paul Tol’s colour schemes and several thematic palettes (geologic timescale, land cover, FAO Soil Reference Groups, etc.) with scales for ggplot2.


Install the released version of khroma from CRAN:


Or install the development version from GitHub with:

# install.packages("devtools")


Paul Tol’s Colour Schemes

Paul Tol offers carefully chosen schemes, ready for each type of data, with colours that are:

All the scales presented in his 2018 technical note [1] are implemented here, for use with graphics or ggplot2.

Qualitative data

Diverging data

Sequential data

Scientific colour schemes

The following scientific colour schemes are available:

More will be added in future releases (suggestions are welcome).

  1. Tol, Paul (2018). Colour Schemes. SRON. Technical Note No. SRON/EPS/TN/09-002. URL: