Secondary names

Volcanite

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Ca$	Calcium	element	0.5 - 0.9		constituent element	main
	$Mg$	Magnesium	element	0 - 1.5		constituent element	main
	$Fe^{2+}$	Iron(II) cation	element	0 - 1.5		constituent element	main
	$Al$	Aluminium	element	0 - 0.5		constituent element	main
	$Si$	Silicon	element	1.5 - 2		constituent element	main
	$O$	Oxygen	element	6		constituent element	main

Composition comments

relatively low in calcium with some disorder of occupancies of Fe2+ and Mg in both octahedral sites - Common substitution: Na, Al, $Fe^{3+}$, Ti (also disordered) - Common impurities: Cr, Mn, Zn, K

Oxides

Formula	$CaO$	$MgO$	$FeO$	$Al_{2}O_{3}$	$SiO_{2}$
Mass fraction (%)	23.2	16.65	6.6	9.4	44.15

Oxides comments

For $(Ca_0.9,Mg_{0.9},Fe^{2+}_{0.2}).(Si_{1.6},Al_{0.4})_2O_6$

Strunz

Class

silicates (09)

Division

inosilicate (09.D)

Family

with 2-periodic single chains, Si2O6; pyroxene family (09.DA)

Code

09.DA.15

Dana

Major class

silicates (VIII)

Class

inosilicate single-width unbranched chains, w=1 (65)

Type

with chains P=2 (65.01)

Group

C2/c clinopyroxenes (Ca clinopyroxenes) (65.01.03a)

Code

65.01.03a.03

Phase type

crystalline

Crystal system

monoclinic

Crystal class

prismatic

Crystal class symbol

2/m (C2h)

Crystal spacegroup

C2/c

Refringence type

biaxial

Refringence sign

positive

Birefringence

0.026

Refraction index $n_{\alpha}$

1.680 - 1.735

Refraction index $n_{\beta}$

1.684 - 1.741

Refraction index $n_{\gamma}$

1.706 - 1.774

Dispersion V

weak to distinct (r > v)

Pure color

brown

Color

green, brown green, light brown, purplish brown, dark brown, black

Diaphaneity

translucent to opaque

Luster

vitreous

Links

• Wikipedia
• Webmineral database
• Mindat
• Handbook of Mineralogy (Min. Soc. Am)