Where do I find Skeletal Tail?

[ZipNac]

Hi,
I need to find the Skeletal Tail. It is the only item I need to complete the Museum collection.
The Wiki says that you can find it either during fishing or in underground mines.
I have fished for 20 straight days from morning 10 PM until night 12 PM. I found it once but the game glitched out when I went to the museum to submit it(I'm using several mods. So not very sure if that caused the game to glitched out. I'm currently using: Gift Taste helper, Harvest with Scythe, Look up anything, loved labels, NPC map location, Skip intro, ♥♥♥ Item sell price and the easier fishing mod).

After spending time fishing I decided to go look for the item in the mines(by using the hoe on the dirt).
On a side note: the underground mines are the one near the Adventurer's guild, right? I ask this because on certain artifacts it specifically says that you need to find it in the dirt(check dwarf scroll 4). So I am really confused here. Where exactly should I look when it says underground mines? I have been looking on floor 91 through 95 because I read on some post that those floors have more dirt.

Also, I just realized that there is an inconsistency on the wiki regarding this artifact. On the Artifacts page of the wiki( http://stardewvalleywiki.com/Artifacts ), it says that this particular artifact can be obtained either by fishing or in the underground mines. On the Skeletal tail artifact page( http://stardewvalleywiki.com/Skeletal_Tail ), it says that this artifact can be obtained either by fishing or through artifact spots. So which is true?

TLDR; Where is the underground mine? And do I need to hoe the dirt to find this artifact?

[timewar]

Either hoe or use a bomb on the dirt in the mine. And yeah it's the one near the adventurer's guild.

[ZipNac]

Thank you @red255 and @timewar :) will do that!

[NoMercy Rider]

I found fishing to be much more lucrative than digging in the mines. Use the magnet bait, treasure hunter tackle, and a +fishing food buff and fish the day away. With all three perks, you pretty much get treasure chests with every cast.

[NoMercy Rider]

Oops... you are correct.