Mosaic Block: A 16-Patch Built from Half Square Triangles
Week five of the Haven Quilt-Along is all about momentum: the Mosaic block is repetitive in the best way. It’s a 16-patch made entirely of half square triangles (HSTs), which means once your process is dialed in, the block becomes a steady, organized rhythm.
The Mosaic block is a 4 × 4 grid—four units across and four units down. When the HSTs are placed intentionally, the block reads as a strong center diamond with lighter corners that “open” the design.
You’ll make four identical Mosaic blocks for the quilt.
Units to Make
Three fabric combinations:
- Background + white (4 units/block; 16 units total)
- Background + medium blue [smokey pink] (6 units/block; 24 units total)
- Background + medium dark green [terracotta] (6 units/block; 24 units total)
Construction method
Place one 4″ square of background fabric and one 4″ square of other fabric right sides together.
Mark the diagonal on the square; this is the cutting line (don’t cut yet!).
Then mark 1⁄4″ on each side of the line; these are the sewing lines.
Sew along both sewing lines. I like to sew just inside the line (towards the cutting
line).
Cut squares along the cutting line and press towards the darker fabric.
- Trim each HST to 3-1/2″ square
Layout the Block
Layout the units using the diagrams for your color way as shown above. Sew four units together to form a row.
Sew rows together to create the block.
I pressed my seams to they would nest when sewing the rows together by pressing towards the blue [smoky pink]. The seam between the white and green [terracotta], I pressed towards the white.
Make four of each block for your colorway. Refer to QAL Guide for fabrics used.
This block finishes at 12½ inches unfinished and surrounds the Dutchman’s Puzzle block from last week.
If you’d like to sew along, the Haven Quilt-Along is completely free and self-paced. You can download the quilt-along guide from my website, follow the video tutorials on YouTube, or join the Haven email list to receive weekly PDF instructions.
Kits available from Vintage Pink & Green (in store or online).