Cast on the sixteenth of Tammuz, worshipped and destroyed on the seventeenth of Tammuz - that is the short history of the eigel hazohov, the golden calf. Delivered and destroyed on the seventeenth of Tammuz - that is, lehavdil, the short history of the luchos, the Ten Commandments.
The Torah does mention the luchos just prior to the unfolding of the eigel narrative in a dangling "one liner" pasuk which is sandwiched between the discussion about the organization of the mishkan and the record of the downward spiral to building the eigel. It reads as follows: (31:18) "Having completed speaking with [Moshe], [Hashem] gave the two luchos of testimony, luchos of stone written with Hashem's finger", and seems to introduce the eigel hazahav story. Rashi says that this pasuk, similar to the detailed mishkan discussion that precedes it, is out of place and belongs after the eigel event. Accordingly, we should certainly try to explain how it enhances the upcoming account of the eigel debacle.
Furthermore, this pasuk will become entirely redundant as we learn of Moshe's descent down the mountain to discover the eigel for himself. That is when we read, "And Moshe turned and descended the mountain with the two luchos of testimony in his hand, luchos that were written on both sides...and the luchos were the work of Hashem, and the writing was Hashem's writing, engraved into the luchos" (32:15-16.) Why then is the stone record of the Ten Commandments, apparently destined to become a gift for our people, mentioned fleetingly in 31:18, with no unique information to offer?
Perhaps the Torah is pointing out to us that in order to appreciate the colossal disappointment of the eigel, one has to fully appreciate what should have happened and what could have been. Of course, to leave the spiritual heights of Sinai and find oneself in the abyss of the eigel, whatever it was and wherever it came from, is the event that we never end probing and testing our ability to understand. But here is another angle that should not get lost: what did we deserve to have? What should we strive to recover? What does a mamleches kohanim, untainted and on course, look like?
It is those questions that must forever accompany the study of this parsha. The mishkan, the parsha that according to Rashi was given to us after the eigel tragedy, precedes it in the written Torah record. Truth be told we envision the mishkan, sans cheit hoeigel, as solidly and closely connected to each and every family thru the first born of the family, all scheduled for mishkan service. After the cheit hoeigel the mishkan "belonged" to one shevet which intercedes for every other non-levite.
We were supposed to have a readily accessible view of Hashem's miraculous handwriting: letters hanging without support, and words engraved in stone that can be read from both sides! All of this to help us become a people among whom the presence of Hashem was palpable! And these are not just the records of what was lost, rather they are testament to a potential - in concept though not in its detailed form - waiting to be regained.
This all may be well summarized by the pithy and encouraging thought of Rav Nachman of Breslov, "if it is possible to ruin, then it is possible to fix."