Which of the following is not correct for black phosphorus?

Black phosphorus has two forms $\mathrm{\alpha }$ and $\mathrm{\beta }$ only. The $\mathrm{\alpha }$-black phosphorus is obtained from red phosphorus by heating it in sealed tube at 803 K. The $\mathrm{\beta }$-black phosphorus is obtained from white phosphorus by heating it at 473 K under very high pressure.