Hermanov sphere (Phlogopite and Anthophyllite)
This specimen is a classic Hermanov sphere, a mineral aggregate characteristic of the Heřmanov locality. It features a distinct zonal structure. The central core is composed of dark brown to blackish phlogopite mica, which displays a typical platy and micaceous habit. Surrounding this core is a thick, radiating rim of anthophyllite. This outer sheath exhibits a fibrous, needle-like texture with crystals oriented radially from the center. The anthophyllite rim is light brown to tan in color and shows a silky luster. The overall morphology is a flattened ovoid or sphere. The specimen appears stable and well-preserved, showing the internal structure of the two distinct mineral phases clearly. The boundary between the micaceous core and the fibrous rim is sharp and well-defined across both images.
KMg3(AlSi3O10)(OH,F)2 + (Mg,Fe)7Si8O22(OH)2
Brown
6.00 Mohs
Good
High collector value
Orthorhombic
Opak
White to grayish-white
Silky luster
Heřmanov
Czech Republic
Side view showing the thickness of the anthophyllite rim and the texture of the phlogopite core.
