Chosam Shel Zahav is Rav Binyomin Zev Horvitz’s kuntres on the identification of the Chilazon used for Techeiles. Its main argument is that the Murex trunculus, known in Hebrew as the argamon keheh kotzim, fits the evidence for the Chilazon of Chazal.
The sefer gathers the major lines of evidence in one place: the Tosefta and Gemara, the simanim of the Chilazon, the writings of the Rishonim, ancient Greek and Roman descriptions of dyeing, archaeological finds, and the practical dyeing process. Rav Horvitz also deals with the common objections, including the lack of continuous mesorah, the phrase “the Techeiles was hidden away,” questions from the Arizal, the color issue, and several sugyos often brought against the Murex identification.
What makes the kuntres valuable is its organized style. Rav Horvitz is not merely saying “the Murex makes sense.” He lays out the sugya piece by piece, showing why the argamon keheh kotzim is not a new guess, but a serious candidate that lines up with the sources, the history, and the actual dye.
