Mineral description : Ilvaite

Ilvaite crystal from Rio Marina, Italy.
Covered by rust and rock crystals.

Mineral class Silicates : Sorosilicates : Gehlenite - Ilvaite group.

Chemical formula CaFe₃OSi₂O₇(OH)

Crystal system Orthorombic or monoclinic.

Habitus Prismatic striated crystals with squarish cross section, massive, columnar or compact.

Cleavage Distinct along the crystal, {001} and {010}, fracture uneven, brittle.

Hardness 5.5 - 6

Density 3.8 - 4.1

Color Dark brown, brownish black to black.

Streak Black, with a brownish or greenish tint.

Luster Submetallic to greasy.

Description

Occurance Most common in contact metamorph rocks. Less commonly in syenites. Also found in metamorphosed limestones and dolostones.

Associates Arsenopyrite, stilbite, hematite, magnetite, pyrite.

Notes Type locality : Rio Marina, Elba, Toscana (Tuscany), Italy.
The name Ilvaite is from the latin name Ilva for the island of Elba.
Easily soluble in hydrocloric acid.
Fuses easily in a flame.
Ilvaite is polymorphic and both orthorombic and monoclinic forms are known.

Localities A rare mineral in scandinavia.
Sweden :

Dannemora mine, Uppland. As derb aggregates.
Långban, Värmland.
Harstigen, Värmland.
Fredriksberg mines, Vetlanda, Jönköping.
Norway :

Bredgangen mine, Fossum iron plant. As irregular masses or well formed crystals.
Skjerpemyr, Grua. As irregular masses or good striated crystals in quartz and feldspar.
Nyseter, Grua. Rare.
Lykkens pröve, Grua. In small amounts.
Rundemyr, Eiker.
Finland :

Viljakkalan Haverin sulphide ore.

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Last changed : 2000-10-26

Mineral class	Silicates : Sorosilicates : Gehlenite - Ilvaite group.
Chemical formula	CaFe₃OSi₂O₇(OH)
Crystal system	Orthorombic or monoclinic.
Habitus	Prismatic striated crystals with squarish cross section, massive, columnar or compact.
Cleavage	Distinct along the crystal, {001} and {010}, fracture uneven, brittle.
Hardness	5.5 - 6
Density	3.8 - 4.1
Color	Dark brown, brownish black to black.
Streak	Black, with a brownish or greenish tint.
Luster	Submetallic to greasy.
Description
Occurance	Most common in contact metamorph rocks. Less commonly in syenites. Also found in metamorphosed limestones and dolostones.
Associates	Arsenopyrite, stilbite, hematite, magnetite, pyrite.
Notes	Type locality : Rio Marina, Elba, Toscana (Tuscany), Italy. The name Ilvaite is from the latin name Ilva for the island of Elba. Easily soluble in hydrocloric acid. Fuses easily in a flame. Ilvaite is polymorphic and both orthorombic and monoclinic forms are known.
Localities	A rare mineral in scandinavia. Sweden : Dannemora mine, Uppland. As derb aggregates. Långban, Värmland. Harstigen, Värmland. Fredriksberg mines, Vetlanda, Jönköping. Norway : Bredgangen mine, Fossum iron plant. As irregular masses or well formed crystals. Skjerpemyr, Grua. As irregular masses or good striated crystals in quartz and feldspar. Nyseter, Grua. Rare. Lykkens pröve, Grua. In small amounts. Rundemyr, Eiker. Finland : Viljakkalan Haverin sulphide ore.