Garnet, usually equigranular, occurs as
euhedral to subhedral large porphyroblasts (up to 1.2 cm diameter), with cores frequently rich in minute inclusions of quartz, plagioclase, graphite and Fe-Ti oxides, and their rims are poorer in inclusions.
The dolomite crystals (Plate 2F) are
euhedral, ferroan in some cases, and are ne sand in size.
Semitransparent layers contain rare medium-crystalline zoned
euhedral dolomite crystals.
Euhedral to subhedral phenocrysts are embedded in an essentially vitreous groundmass with plagioclase and pyroxene microlites.
They are composed of
euhedral to subhedral, coarsely perthitic alkali feldspar and varying amounts of interstitial quartz (Fig.
The most sought-after specimens are those displaying transparent,
euhedral, aquamarine-blue, pseudo-cubic to pseudotetrahedral crystals.
The fine-grained
euhedral pyrite Py(s) of this stage is 10 to 50 [micro]m in size and is disseminated within dolomite with the hydrothermal minerals filling interspace (Figure 4(b)).
Amphibole phenocrysts are 1-3 mm in size, are
euhedral, have rhombus-shaped cross-sections, and are rimmed by opaque magnetite (Fig.
These rocks are medium- to coarse-grained equigranular to inequigranular anhedral to
euhedral with xenomorphic to idiomorphic granular texture.
Dolomite cement occurs as
euhedral to subhedral crystals filling pore spaces and is rimming detrital grains.
Biotite occurs as fresh anhedral to
euhedral microlites.
And here's what I mean about fun facts: we are authoritatively clued in about those intriguing, earthy gray-brown pseudocrystals from Siberia which are sometimes called "achtaragdite": they are pseudomorphs of an intermediary solid solution between grossular and katoite after
euhedral crystals of mayenite, an extremely rare, poorly characterized Ca-Al oxide.