Perhaps I am overlooking something in my research so I need some help understanding something.
1) The command to wear Tzitzit was given in the wilderness of the desert.
2) The chilazon of talmud is a sea creature, whether fish or mollusk.
3) Leviticus and Deuteronomy both say that fish without fins and scales are a detestable and unclean to us.
4) Where, in the desert did we find these mollusks or cuttlefish?
5) How can we touch the Torah with tzitzit that has been dyed blue (tekelet) by an unclean and detestable thing?
6) LXX translates the word to hyacinth. Why the difference?
I gather that tekelet simply means the color blue or a shade thereof.
If the thread in tzitzit was dyed using the indigo or any other plant, well and good.
But if the dye was from something which Torah calls, " detestable", it could not possibly have been used. It would seem to fall in the category of touching a carcase.
The High Priest's clothing could never have been dyed with such a thing. The indigo plant is native to the entire middle east and would make sense. So my point, again, is:
If dyed with a detestable, unclean animal how could the High Priest's clothing be holy?
How could the tzitzit be allowed to touch a Torah scroll.
Caladan's right-- techeilet comes from the Tyrian murex sea snail. There are several Orthodox sources that agree with this.
But there are many examples in halachah of instances where an animal itself may be unkosher, but products made from it (things not intended for eating or drinking) may be permissible to use under certain circumstances. Bees and honey, as rakhel said, is even an example where the animal is unkosher and we can eat what it produces. But, for example, horses are unkosher, and yet one is permitted to wear, say, a belt made of horse hide. Pigs are unkosher, and yet one is permitted to wear, say, shoes made of pigskin leather.
It is also the case that sometimes the Torah can command us to do things in specific circumstances that might be prohibited in other circumstances, and we do them because we are commanded to do them, and not because we might be commanded against them in other cases. For example,
yibum (levirate marriage): normally, a brother's wife is prohibited to a man-- it would usually be one of the
arayot. But in the case of
yibum, a man is specifically commanded to sleep with his brother's wife.
The LXX translates it as
hyakinthos because it was unsure about the Tyrian murex snail, and because in the time of the Septuagint, a popular purplish dye was distilled from the hyacinth flower.
But we never actually made the techeilet. We purchased it. Not only because we weren't near an ocean while we were in the wilderness, but because it would have been difficult for us to make it in a ritually pure way. The Tyrians made it, and we either purchased it from caravans travelling through the wilderness, or we took it with us from Egypt when we went out.
In any case, though, even if there were a question of
tum'ah from the techeilet, it wouldn't be a problem to touch a Torah scroll with it, because a
sefer Torah is not susceptible to
tum'ah-- it cannot become
tamei. The only question would involve
kavod, since normally we do not approach a Torah scroll with
tamei things out of respect-- but since we are commanded to wear techeilet, this should not be an overriding issue.