I've traced an individual's line back to an 1850 orphan who was variously identified as Black, Mulatto, Irish, and White on the different documentation I've found. Based on this documentation & family lore, I believe he may have been half Irish & half Black.

There are no males to be tested in this line but the female willing to be tested is the great-granddaughter of the ancestor in question, following a male line down to her.

Is there any DNA test she can have that will confirm the Black ancestry?

An autosomal test like the new ancestrydna test, the Family Tree DNA Family Finder test, or 23andme's dna test should show if a person has African/Black ancestry. Since a person receives half of their dna from each parent, male of female, anyone can take an autosomal test to find possible ancestry from any ancestor on any line of descent. Unlike a Ydna test which will only trace the Y line from male to male or the Mitochondrial (Mtdna) test which tests the line from a persons mother-to grandmother-to greatgrandmother etc. Hope that helps.

Yes, thank you, it is helpful.