We present a comprehensive study (scanning electron microscopy, energy dispersive X-ray spectroscopy, single crystal X-ray diffraction, IR and Raman spectroscopy) on the synthetic mica with the chemical formula K2Mg5.019Al0.031Si7.949O20(OH)4. Spontaneous mica crystals up to 1 mm in size were synthesized in a hydro-thermal gradient condition at temperature 600/650 degrees C and pressure of 150 MPa in high gas pressure vessels. By the chemical composition the synthesized mica corresponds to Mg-analogue of montdorite and (OH)-analogue of yangzhumingite. The unit cell parameters are: a = 5.2599 (1)& Aring;, b = 9.1056 (1) & Aring;, c = 10.1917 (1) & Aring;, beta = 99.969 (1)degrees, space group C2/m. IR-and Raman spectra were obtained at the ambient conditions and described. Using in situ Raman spectroscopy at high pressures, the dependence of the shift in the position of the main bands of the synthetic mica Raman spectrum on the pressure was established. According to the data of Raman spectroscopy up to--30 GPa, it was revealed that the synthetic mica undergoes the possible structural changes at--7 and-- 18 GPa.