Answers to “What ancient practice did Jesus have in mind, when he said of salt being thrown out as waste?” indicate that the word “salt” doesn't necessarily mean table salt, but can include salts of calcium, potassium, magnesium, etc.
Strong's Definitions for מֶלַח H4417 - melaḥ says:
properly, powder, i.e. (specifically) salt (as easily pulverized and dissolved)
So, it wouldn't be unreasonable to translate Genesis 19:26 as:
But his wife looked back from behind him, and she became a pillar of powder [or dust].
The question though is about the word commonly translated as “pillar” in English and as “statue” in Romance languages.
נְצִיב H5333 - nᵊṣîḇ:
something stationary, i.e. a prefect, a military post, a statue: — garrison, officer, pillar.
Of the 12 occurrences in the Bible, only one is translated as “pillar”; all the rest are translated as “garrison” or “officer”.
What are the reasons for the specific idea of a “pillar” or “statue”, especially when related to something that is composed of powder?
(For instance, why would “pile of dust” or even “pile of powdered bones” be inappropriate?)