Have a look at the sand and soul sand quests to see if they are as clear as possible.

Back when I added sand/glass to the gems/metals page, I knew there was possibility it was rather hidden there and it might be difficult for users to spot. Well I recently just had that problem with a user not seeing it and struggling to figure out where the best source of sand is.

They recommended putting the sand quest around the 'sand casts' quest, which is when I told them soul sand could be used for the quest. I should review all the quests involved, improve their language if they're inadequate, and consider adding another, optional sand quest to the Smithy page to catch more people.