Sadanagaite (original) (raw)

Formula:

{Na}{Ca2}{Mg3Al2}(Si5Al3O22)(OH)2

The sadanagaite group minerals are defined as with 0.5 < A(Na+K+ 2Ca) where Na or K is dominant, and with 1.5 < C(Al+Fe3++2Ti), where Al or Fe3+ are dominant. The W position may contain (OH), F or Cl.

Sadanagaite is defined with
A position: Na dominant
C2+ position: Mg dominant
C3+ position: Al dominant
W position: (OH) dominant.

Specific Gravity:

3.30 (Calculated)

Crystal System:

Monoclinic

Name:

Named in honor of Ryoichi Sadanaga (定永両一) (25 June 1920, Osaka, Japan - 17 January 2002), crystallographer and professor of the Mineralogical Institute, University of Tokyo. He also held the post of President for both the the Crystallographic Society of Japan and the Mineralogical Society of Japan.

Sadanagaite was first described as a new silica-poor amphibole (IMA 1980-027), published by Shimazaki et al. (1984). It was redefined in the 1997 amphibole nomenclature (Leake et al., 1997). The original definition of sadanagaite has K>Na in the A position, this was reversed in 1997. It should also be noted that there is a probable typo in the 1997 nomenclature report, defining sadanagaite with Fe3+>Al in the formula, which has led some authors to use the term aluminosadanagaite (see Nikandrov et al., 2001).

Sadanagaite was again redefined in the 2012 amphibole nomenclature to be the Na-, Mg- and Al-dominant member of the sadanagaite group (Hawthorne et al., 2012).

Consequently, the material originally described as sadanagaite in 1984, became potassic-sadanagaite in 1997 and potassic-ferro-sadanagaite in 2012.

Na- and Fe2+-dominant material described as sadanagaite between 1997 and 2012 is now (2012) ferro-sadanagaite.

The material described by Banno et al. (2003) as magnesiosadanagaite was defined as sadanagaite in the 2012 ampibole nomenclature.

This page provides mineralogical data about Sadanagaite.

RI values:

_n_α = 1.673(2) _n_β = 1.684(2) _n_γ = 1.697(2)

2V:

Measured: 70° to 90°, Calculated: 86°

δ = 0.024

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Dispersion:

r > v perceptible

Comments:

X = pale brown, grayish, or greenish yellow; Y = yellowish orange to light olive-brown; Z = greenish brown, light olive-brown to dark yellowish orange

Crystal System:

Monoclinic

Cell Parameters:

a = 9.922(10) Å, b = 18.03(2) Å, c = 5.352(9) Å
β = 105.3(10)°

Ratio:

a:b:c = 0.55 : 1 : 0.297

Unit Cell V:

923.50 ų (Calculated from Unit Cell)

Comment:

Point Group: m; 2; or 2/m:; Space Group: C2; Cm; or C2/m:

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