Sample extremely sensitive to hand-pressure,
leading to an extraordinary preferred orientation effect.

Pressing the sample on a glass slide :

Dusting the sample through a sieve :

Identification is positive by a default search in the PDF-2 database :

Zeropoint evaluated by the harmonics method,
refining fictitious cell parameters.
 
 

TREOR90 tests in monoclinic symmetry allow to obtain a proposition after having increased the maximum cell volume successively to 200, 400, 600, 800, 1000 and finally 1200 A³.

ITO does not provide the same cell.
 

DICVOL91 gives the same result as TREOR90.
 

Ultimate verification of the cell quality.

The P2₁/c space group is suggested.