How do you identify a Phenakite?

Phenakite occurs in the rhombohedral division of the hexagonal crystal system. If you look carefully, crystals are usually clearly hexagonal (Figs. 1, 2), which helps one to distinguish phenakite from topaz, whose orthorhombic crystals are often rectangular or diamond shaped in cross section.

How can you tell the difference between quartz and phenakite?

Phenakite is harder than quartz and at 7.5-8 on the Mohs scale–nearly as hard as topaz. It also has a higher refractive index at 1.650-1.695. This makes it both more durable and more brilliant.

What does phenakite look like?

It is often colourless and glassy but may be wine yellow, pale rose, or brown. Its indices of refraction are higher than those of quartz, beryl, or topaz; it is consequently rather brilliant and may sometimes be mistaken for diamond.

Is phenakite a Tektite?

There is no cleavage, and the fracture is conchoidal. The Mohs hardness is high, being 7.5 – 8; the specific gravity is 2.96….

Phenakite
Unit cell	a = 12.438 Å, c = 8.231 Å; Z = 18
Identification
Color	Colorless, yellow, pink, brown

Why is K-feldspar pink?

K–feldspar albite intergrowths known as pertite and albite intergrowths K–feldspar as antipertite. The hardness is from 6 to 6.5 and the relative density of 2.55–2.63. The color is usually white, and sometimes changes from pale pink to reddish due to admixtures of iron (especially microcline).

What is Carlsbad twinning?

A twinned crystal in which the twinning axis is the c axis, the operation is a rotation of 180 degrees, and the contact surface is parallel to the side pinacoid. It is quite common in the alkali feldspars. An alternative spelling is Karlsbad twin. Carlsbad twin of feldspar.

How do you identify a microcline in the thin section?

Microcline is often characterized by a distinctive plaid (cross-hatched) twinning (also known as tartan twinning), giving a zebra stripe appearance. This type is also called gridiron or quadrille structure, the two sets or lamellae being at right angles.

Is phenakite the same as Phenacite?

phenakite, also spelled Phenacite, rare mineral, beryllium silicate, Be2SiO4, used as a gemstone.

What color is phenakite?

Phenakite is a very rare silicate gemstone. While it can be colored a pale blue or yellow/sherry color when it comes out of the ground, the color almost always disappears when its exposed to light.

What rocks have K-feldspar?

K-feldspar. K-feldspar is widespread and common in a wide variety of igneous and metamorphic rocks and in some sedimentary rocks.

What is albite law?

[′al‚bīt ‚lȯ] (crystallography) A rule specifying the orientation of alternating lamellae in multiple twin feldspar crystals; the twinning plane is brachypinacoid and is common in albite.

What is aenigmatite made of?

Aenigmatite ( IMA symbol: Aen ), also known as Cossyrite after Cossyra, the ancient name of Pantelleria, is a sodium, iron, titanium inosilicate mineral. The chemical formula is Na 2 Fe 2+5 TiSi 6 O 20 and its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches.

Where is aenigmatite found in nature?

Aenigmatite is primarily found in peralkaline volcanic rocks, pegmatites, and granites as well as silica-poor intrusive rocks. It was first described by August Breithaupt in 1865 for an occurrence in the Ilimaussaq intrusive complex of southwest Greenland.

What is the formula for aenigmatite?

Aenigmatite forms a solid-solution series with wilkinsonite, Na 2 Fe 2+4 Fe 3+2 Si 6 O 20 . Aenigmatite is primarily found in peralkaline volcanic rocks, pegmatites, and granites as well as silica-poor intrusive rocks. It was first described by August Breithaupt in 1865 for an occurrence in the Ilimaussaq intrusive complex of southwest Greenland.

What is aquamarine used for?

In granite pegmatite s. Aquamarine is the most popular light-blue gemstone, and is extensively used in jewelry. Rings, earrings, and bracelets are made from Aquamarine, and it is especially important as a pendant stone, with fairly large pendants being facet ed from Aquamarine.