parshat Terumah: The Identification of tekhelet

Ibn Ezra has an interesting comment on Shemot 25:4:

ד וּתְכֵלֶת וְאַרְגָּמָן וְתוֹלַעַת שָׁנִי, וְשֵׁשׁ וְעִזִּים.

4 and blue, and purple, and scarlet, and fine linen, and goats' hair;

אמר יפת שהוא כדמות שחרות. כי הוא תכלית כל הצבעים. והכל ישובו אליו והוא לא ישוב במעשה אדם לעולם. ואנו נסמוך על רז"ל שהוא ירוק והוא צמר

He cites Yefet, who claims that tekhelet is a type of shachor (black) and gives an derivation for this (please correct me in the comments, since I do not feel entirely comfortable with this translation):
All the other colors end in it, and eventually come to it, but black cannot ever become another color by human action.

Thus, it is perfectly described by the כלה, end, that lies at the root of the word tekhelet.
After citing Yefet, Ibn Ezra writes that we rely upon our Rabbis, of blessed memory, who says that it is yarok (blue being in the "green" family).

This is an interesting comment by Yefet. He comes to an identification of color by (philisophically) reasoning what color is best described by the root. At the heart of this seems to lie an approach to linguistics that natural language is sytematic and regular, such that the meaning of any word can be derived from an analysis of its root. Yet often natural language is not systematic in this way - as words come from other languages, or change in meaning over time as people use it in different ways, etc.

In this instance, it seems particularly ill-advised to derive meaning from such an analysis. Even if the root does mean "end," how do we know that the derivation should be made in this particular manner. I could give similar rationalizations for an identification with red (an association with blood and thus death) or white (absence of dye or color). The explanation seems scientific but it is not. Furthermore, we have a tradition from Chazal. Yefet is a Karaite, so he does not put stock in Chazal, but in this case, it is entirely reasonable to accept the Masorah on this. After all, Chazal saw tekhelet. Even as tekhelet was not in use in the days of the Rishonim, it was in use in the days of Chazal. And it was not just Pharisees who used it, but other groups and nations as well. They are giving testimony of a well-known color in their days. Discarding this testimony in favor of a speculative derivation based on the apparent root makes no sense.

Indeed, we have recently found corroborating evidence to the blueness of tekhelet, at least in the time of Chazal, in the form of tzitzit dyed with fake tekhelet - kala ilan - around the Bar Kochba caves. (And it is the same color, and of similar chemical composition, to murex tekhelet.)

As I noted above, Yefet is Yefet ben Ali, a 10th century Karaite who Ibn Ezra often cites. Thus we can expect him to differ from Chazal in respect to this identification, or at least it is not truly suprising. I would like to see Yefet inside, so if anyone knows of an online text or has access to it, I'd appreciate any help.

What is interesting is that Rambam also identifies tekhelet as black! In Mishneh Torah, in Hilchot Tzitzit 2:1, we read:

א תכלת האמורה בתורה בכל מקום, היא הצמר הצבוע כפתוך שבכוחל; וזו היא דמות הרקיע, הנראית לעין בטוהרו של רקיע. והתכלת האמורה בציצית, צריך שתהא צביעתה צביעה ידועה, שעומדת ביופייה, ולא תשתנה. וכל שלא נצבע באותה הצביעה, פסול לציצית: אף על פי שהוא כעין הרקיע, כגון שצבעו באיסטיס או בשאר המשחירין--הרי זה פסול לציצית. ורחל בת עז, צמרה פסול לציצית.

Thus, he identifies it as a particular shade of black, and notes that other black dyes are not fit for tzitzit.
Tekhelet, he claims, is wool dyed like the mixture in a kochal - stibium. kochal was used as a powder for painting eyelids, and Chazal refer to the blackness of kochal, saying in Chullin 47b that something is as black as kochal.

This certainly reads like Rambam is saying that tekhelet is black. And that Chazal's statement that it is comparable to the sky is that it is comparable to the night (rather than day) sky. Yet apparently (see this post on Maven Yavin by lamedzayin and his response to my comment there),

The Beis Yosef reads the Rambam that way, but most people assume he means a darkish blue and just that the ink itself is black, not the final dyed product.

I find this reading difficult. kochal seems to be black. Now, Jastrow translates kochal as stibium, and according to Webster's, stibium is either the chemical name for antimony (which is whitish blue, and not black), or in archaic usage, stibium is stibnite, the natural sulfide of antimony, which is a mineral which is steel-gray to dull-gray. Follow the link to see a picture. The latter seems more likely. And as the wikipedia article on antimony states, it is stibnite, and not antimony, which known as Biblical times and was used as a medicine and a cosmetic. So it stands to reason that kochal is exactly this - stibnite (Sb₂S₃).

As I said, kochal seems to be black, not darkish blue, and the Rambam explicitly states that the wool is dyed black, so it is difficult to see how one can say it is the ink and not the dyed product which looks like kochal. I won't rule out alternate readings but I would need some compelling proof before accepting one of these alternate readings.

Presumably, what influenced these alternate readings is the difficulty the contradiction between the Rambam's words and the various statements of Chazal that suggest that it is yarok. Thus, there are attempts at harmonization.

However, now that we see that there were people contemporary to Rambam (Karaites) who held that it was black and not blue, and those who recognized that this was a dispute with Chazal's identification, we should expect for Rambam to be extremely clear if he talks of it as black. He should say that it is the dye, not the wool, that is black, or should mention yarok somewhere.

No, what seems to be happening is that Rambam is actually adopting the modern (for his day) "scientific" and philosophical identification of tekhelet and rereading Chazal (in terms of the midrash about being similar to the rakia) so that they agree with this modern definition. And since this is a definition with no basis except a shaky Karaitic linguistic argument, we should pay it no heed in terms of considering this Rambam to be an impediment to recognizing genuine tekhelet - the murex stuff.

Update: On the other hand, Rambam does not identify this as the color of kochal, but rather at the pitukh which is in kochal. Now, pitukh is a mixture, an 'eruv or meziga. Now, we know that powedered coal was mixed with stibium (see Chullin 88b), so that, together with references to "other blackening agents," strongly suggests black. Perhaps, though, one might say that it refers to the "tarnish" on stibnite. According to wikipedia, the color of stibnite:

Steel gray to dull gray. Black iridiscent tarnish may be present.

So once again we would have black.