Three of the many fragments of dyed textiles and fibers from Timna that were analyzed, yielded results compatible with true purple dyestuff

https://www.timesofisrael.com/ancient-cloths-with-royal-purple-dye-found-in-israel-dated-to-king-davids-time/

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245897