Is this Celery salt?

Many months ago a friend friend gave me some "Celery Salt" (Something to do with spice for eggs - also something of a British/English tradition). This "Celery Salt" was just in a small jar (ie no manufacturer labelling). My friend can't recall the details of it.

I understand (maybe wrongly) that Celery Salt is Celery leaves + salt. I have tried to make Celery salt by drying Celery leaves, crushing them [but maybe not fine enough ?] and adding salt - and this is interesting but very different to what she gave me.

When I look in the local supermarket, I can buy "Celery seeds" (but not Celery Salt, or Dried Celery). I am wondering if what she provided is actually a Celery Seed + Salt. Can anyone give me an opinion as to what it actually is. Below are the pictures (one zoomed in), one showing it more how it looks to the naked eye -

Celery salt is made from salt and ground celery seed. It would probably be possible to make something with a similar taste using dehydrated celery leaves/stalks/juice but I’ve never seen that done.