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Minerals - Sturmanite | TerraCollect

Mineral - Sturmanite

SturmaniteCa₆Fe³⁺₂(SO₄)₂,5[B(OH)₄](OH)₁₂ · 25H₂O

Chemical Properties

Mineral Class

Sulphates

Toxicity

none

Formula

Ca₆Fe³⁺₂(SO₄)₂,5[B(OH)₄](OH)₁₂ · 25H₂O

Unit Cell

a=11.16 c=21.79 Z=2

Physical Properties

Hardness

2.5

Streak

yellow

Density

Light (<2)

Optical Properties

Color

brownorangeyellow

Birefringence

0.005

Luster

Vitreous,

Greasy

Transparency

translucent,

transparent,

opaque

Pleochroism

Geomineralogical Properties

Crystal System

Composition

Elements

Mass

SO₃

14.20

B₂O₃

3.20

Al₂O₃

1.13

Fe₂O₃

8.84

MnO

1.30

CaO

25.60

H₂O

46.70

South Africa (Peacor et al. 1983)

Karten-Ebenen

Geologische KarteSatelliten Karte

Cleavage

Perfect after {1010}

Fracture

uneven

Tenacity

Brittle

trigonal

Point Group

ditrigonal-pyramidal - 3m

Space Group

P31c (159)

Habit

blocky, dipyramidal, lenticular, prismatic, tabular, barrel-shaped

Formation

Secondary, formed under low-temperature hydrothermal conditions in fractures and cavities of metasomatically altered manganese deposits

Paragenesis

Twinning

Rarity

Very rare

Synonyms

Sturmanite

Groups and Members

Ettringite-Group