Not Visible and no drive letter, lists as Drive 5 Healthy (Unknown
Partition).
There won't be a drive letter till after you format it to a filesystem
which Windows understands, such as FAT32 or NTFS. The Healthy Unknown
Partition is any partition that is not native to Windows. You'll see the
same description of Linux partitions if you have a dual-boot hard drive
with multiple partitions in it. The ones that Windows doesn't understand
are described as Unknown.
Just right-click on the Unknown partition and Windows will delete it for
you. You will then be left with an Unallocated Space in that drive,
which you can then right-click and create what's called a simple volume
on it, which is basically a FAT or NTFS partition.
Yousuf Khan