The block design from this late 19th or early 20th century quilt is very unusual. The quilt, a recent addition to my collection, came from The Quilt Complex. It's an offbeat, inside-out way of looking at the block pattern known as New York Beauty, and this block is really the section that would ordinarily be the intersecting point of four blocks and the sashing grid.
Here's how the traditional block looks when surrounded by sashing and cornerstones, followed by a squared version of the first block for comparison. The similarity in colors makes the differences even more clear.
The unusual block design is an X-shaped pattern when set as a square. The cornerstone, often a star or sun with rays, is a circle made of eight wedges alternating between two colors. In the quilt, the block is turned on point and placed in offset rows, creating a secondary zig-zag pattern with the negative space.
The zig-zags are made with a small-scale print, and they act as the sashing of the quilt. In the traditional quilt, sashing includes pieced points running along both edges of a strip, and the sashing usually forms a grid.
In most of the 19th century examples, the grid is vertical-horizontal rather than diagonal. In the 20th century, the diagonal became more popular with the publication of the Mountain Mist design. Turning the design on the diagonal simplified it, and reduced the number of blocks and amount of piecing in the quilt.
Tim Latimer, quilt sleuth an hand quilter extraordinaire, identified the unusual block design as The American Woman's Own Quilt Block (8) from Hearth and Home, Brackman #3558. Good eye, Tim!