Hello Carla,
Richard may be indexed incorrectly as white in 1870 - but the actual record lists him as black, and gives his birthplace as PA.

Name: Richard Coleman
Estimated birth year: abt 1845
Age in 1870: 25
Birthplace: Pennsylvania
Home in 1870: Scott, Allegheny, Pennsylvania
Race: White
Gender: Male
Post Office: Green Tree

Richard 25 black farmer b. PA
Eliza 30 black housekeeper b. PA
Mary 12 b. PA
Susan 5 b. PA
Richard 4 b.PA
George R 1 b. PA

What is curious about this record is Mary - who seems a bit old to be Richard's daughter (he would have been 13 at the time of her birth) - and she isn't in household in 1880. Since relationships aren't listed in 1870 she may be either Eliza's daughter (using name Coleman) or Richard's sister. The age difference between Richard and Eliza remains consistant in 1880.

Have you checked for birth records for the children?

I would check 1860 records to see if they were free in PA or VA.

Here is the 1880 index listing at ancestry which shifts birthplace to E. VA. I would investigate the boarders - sometimes they are cousins, listed as boarders:

Name: Richard Coleman
Home in 1880: Mansfield, Allegheny, Pennsylvania
Age: 36
Estimated birth year: abt 1844
Birthplace: E VA
Relation to head-of-household: Head
Spouse's name: Eliza J.
Father's birthplace: E VA
Mother's birthplace: E VA

Occupation: Laborer
Marital Status: Married
Race: Black
Gender: Male

Household Members: Name Age
Richard Coleman 36 B b. E. Va
Eliza J. Coleman 41 Mu b. E. Va
Suscy Coleman 17 Mu b. PA
Richard Coleman 14 Mu
George Coleman 11 Mu
Katie Coleman 9 Mu
Lilley Coleman 4 Mu
Ellen Coleman 1 Mu
Howard Coleman 3M Mu
H. K. Johnson 38 Mu boarder b. E. Va
G. H. Johnson 7 Mu boarder b. PA
Chas Anderson 22 Mu boarder b. E. Va