Phengite is an aluminous true mica which contains a relatively high amount of tetrahedrally co-ordinated Si (>3.1 apfu). As the Si amount increases, additional octahedrally co-ordinated cations are necessary for charge balance.

It is clear with a pearly luster on cleavage faces, often having a sparkly look in rocks. It can form a continuous series with celadonite and aluminoceladonite; intermediates are known as the variety phengite and K-deficient variants as illite.

In these sections, some of the primary K-feldspar is preserved, and phengite occurs at the rims of the larger K-feldspar grains, and also replaces all plagioclase grains and some small...

Phengite is a series name for dioctahedral micas of composition K(Al,Mg) 2 (OH) 2 (Si,Al) 4 O 10. It is common for Mg or Fe 2+ to substitute for Al on the Y site and a corresponding increase in Si on the Z site in the mica group formula X 2 Y 4–6 Z 8 O 20 (OH, F) 4. Similar to muscovite but with addition of magnesium.

The three types of phengite series that occurred from the Haengmae Formation are defined micro-texturally as polycrystalline aggregates (Type 1), pore-fillings (Type 2) and well-crystallized lath...

Rock-forming minerals of metamorphic rocks, in thin section (a work in progress)

Textural‐petrographic‐compositional observations reveal that the polygenetic WM consists of five different generations: pre‐Eocene relicts, paragonite, high‐Si phengite, low‐Si phengite ...

2013年9月1日 · Using the depth profile created by plotting the intensity of the Al–OH spectral feature, sections of the drill core that contain a high abundance of phengite can easily be identified. The phengite-poor sections are those where the second derivative intensities are near zero, and the second derivative intensities increase with the amount of ...

Glaucophane-phengite-garnet-clinozoisite (rutile) gneiss (the section is deliberately thick, to highlight the pleochroism of glaucophane. The rock has a strong lineation (clinozoisite-glaucophane) and foliation (phengite), section cut parallel to …

2013年9月1日 · The thin sections from the five selected phengite-bearing samples show visible differences in composition and texture (Fig. 4). The two samples collected from the ore-bearing, brecciated zone (OD05 and OD12) have been completely transformed by sericitic alteration—and as a consequence, any type of feldspar is absent (Fig. 4A, B).