This is Snowflake #46 in the book of 100 Snowflakes. Instructions are on Page 69. It is pictured on page 29 in the showcase.

“Aufeis II begins with the first four rounds of Aufeis I, and then adds two more thick rounds, to build a larger, but equally solid, snowflake.”

Finished diameter: 2 7/8 in (73 mm)
Thread required: 10 yd (9.1 m)

All pattern samples in this book are made with size 10 thread and a size 5 (1.9 mm) crochet hook.