Loomi powder comes from powdered black limes, Citrus aurantifolia. Black limes are whole, sun-dried limes. These are 2.5-4cm in diameter (1-1.5 inches).

The limes are picked, then boiled in salt water, before being dried out in the sun. Black limes have a colour that ranges from a light tan colour through to a very dark brown, which is almost black, with around 10 darker tan longitudinal stripes going from end to end. Inside the broken black limes, there is a dark sticky pith that has a pungent citrus aroma.

Originally, black limes came from Persia, so sometimes particular people call for a black Persian lime.