V.V. Rankine, a Washington artist who has not quite had her due in this city, is showing sculpture from the past two years at Barbara Fiedler Gallery. Appropriately titled "Black Transition," it is an important show for Rankine, marking not only a major shift away from pure abstract formalism, but a move toward a more profound, humanistic expression through the use of architectural forms. In both respects, her work parallels what is happening in much of the more advanced art currently being produced -- as, indeed, her work always has.

This show will come as a surprise to those who best remember Rankine for the austere, minimal shaped canvases and columnar sculptures she showed at Jefferson Place Gallery a decade ago. She has since explored various modes in wood and plexiglass sculpture, the latter of which has come to fruition here.

But while these works of cut and joined bronze and gray plexi relate to the earlier abstract columns, those columns have now been transformed, in essence, into dark, smoky vitrines that contain stripped-down architectural forms, notably the dark (Home) and (Place), both of which consist of childlike houses that stand encased at the top of a squared, transparent column. Both evoke a gentle, essentially romantic sense of nostalgia, perhaps issuing from some deeply buried memory of a reconverted country schoolhouse in which the artist once lived.

But it is in the back room at Fiedler where the "black transition" of the title actually takes place, and where the mood also shifts dramatically to one of forboding in several stark black works in the form of medieval castles, Mayan structures and the Washington Monument. Now having burst forth from any enclosure, these pieces assert themselves as ominous presences. They have also been freed from the elegant, light-reflecting surface qualities of plastic by a sanding process the artist has devised to give them the matte texture of stone or clay.

"They come from the mood of Washington, which I think is becoming more and more somber," says the artist, adding that the sense of presentiment or forboding was, indeed, intended. The Washington Monument is not often thought of as an expressive sculptural form, but Rankine has surely transformed it into precisely that in the mysterious works she has created here.

The show continues through January, and can be seen at 1621 21st St. NW, Tuesdays through Saturdays, 11 to 5. Upstairs are some interesting clay plaques made in Bennington in 1964 by David Smith, Helen Frankenthaler and others.