enstatite — species of mineral; see enstatite in ‘Classification’ …
epidote — species of mineral; see epidote in ‘Classification’ …
euclase — species of mineral; see euclase in ‘Classification’ …
eudialyte — species of mineral; data; faceted specimens exist …
extrusive — mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes into the atmosphere to fall back as pyroclastics or tuff …
fan — rare shape in faceting a gemstone …
felsic — refers to igneous rocks that are relatively rich in elements that form feldspar and quartz …
ferro-actinolite — species of mineral; data; constituent of nephrite …
ferro-actinolite-tremolite series — a series between ferro-actinolite and tremolite; see ferro-actinolite-tremolite series in ‘Classification’ …
fluorapatite — species of mineral; see fluorapatite in ‘Classification’ …
fluorite — species of mineral; see fluorite in ‘Classification’ …
forsterite — species of mineral; see forsterite in ‘Classification’ …
freibergite — species of mineral; data; faceted specimens exist …
friedelite — species of mineral; see friedelite in ‘Classification’ …
fumarole — an opening in a Earth’s crust, often in the neighborhood of volcano, which emits steam and gases …
gadolinite-(Y) — species of mineral; see gadolinite-(Y) in ‘Classification’ …
gahnite — species of mineral; data; faceted specimens reported …
gedrite — species of mineral; data; constituent of nuummite …
girdle — a small belt separating the two parts of faceted stone — crown and pavilion …
glass — natural glass; see also tektite …
