English: Crystal structure of CaSi2. Created using Diamond 4. Data from Fahy, S.; Hamann, D.R. Electronic and structural properties of Ca Si2 Physical Review, Serie 3. B - Condensed Matter (18,1978-), 41, 7587-7592 (1990)
The figure shows 1P-CaSi₂, the simplest variant of a CaSi₂ structure formed under high pressure. In addition, stacking variants such as 3R-CaSi₂, 6R-CaSi₂, and 21R-CaSi₂ exist, each with a correspondingly longer c-axis.