Mrs. Black in French is Madame Black, abbreviated Mme. Black. Note that one does not translate the surname, Black. The common noun black is "noir" in French, but one would never address this woman as Madame Noir.
It depends on the "Mrs." you are addressing. I could be either Madam or another variety of "Mrs."
pitch black is translated 'nuit noire' in French.
Black gloves are 'des gants noirs' in French.
bonjour madame Knight
bonjour, madame Ann.
Je m'appelle madame Mason
in French, black beauty is 'beauté noire'
A beautifu black butterfly is "un beau papillon noir" in French.
cheveux noir
Noir.
coeur noir
cheveux noirs