Mineral description : Stilbite (Desmin)

Picture pending, stilbite from Kiruna.

Stilbite from India. Stilbite from Sulitjelma, Norway. Stilbite from Leveniämi, Svappavara.

Mineral class Silicates : Tekto silicates : Zeolites

Chemical formula CaAl₂Si₇O₁₈*6H₂O (Mineral i Sverige)
CaAl₂Si₇O₁₈*7H₂O (Mineraler, stenar och ädelstenar)
(Ca,Na₂,K₂)[Al₂Si₇O₁₈]*7H₂O (Mineraler och bergarter)
NaCa₂Al₅Si₁₃O₃₆*14H₂O (Norsk steinbok) (Bergarter, mineral, fossil)
(There seems to be some difference between books about the chemical formula)

Crystal system Monocline

Habitus Prismatic crystals, often as leaf formed crystals of twins or fibric radiating aggregates.

Cleavage One complete cleavage. Uneven fracture.

Hardness 3.5-4

Density 2.1

Color White, yellow, grey to reddish brown. Often translucent.

Streak White.

Luster Glas to pearly.

Description

Occurance Oftly created in cavities in basaltic rocks. More seldom in methamorphic rocks.

Associates Heulandite.

Notes All zeolites are soluble in strong hydrocloric acid when powdered, leaves silicagel as a rest. The water is driven out when heated. Melted by a micro flame.

Locations Not so common in Sweden.

Fröå mine, Åreskutan, Jämtland. As drusy fillings in cracks together with chabasite.
Fridhems mine, Gällivare. Common together with chabasite in drusy goldbearing quartz.
Malmberget iron mine, Gällivare. As yellow round aggregates together with chabasite in holes in metabasite and scarn.
Svappavaara mine. As in Malmberget.
The most common zeolite mineral of Norway.

Gjörvik, in a big quarry. In cracks and holes in a gneiss. Together with chabasite.
Vestlandet. A very common mineral here, found in most roadcuttings and tunnels together with laumontite and calsite. For example in : Dale (railwaytunnel), tunnels and roads at Hellesylt, Geiranger-Norddal and Gurksköy.
Svenningsdal. Crystal masses of stilbite fills out the room after calcite crystals. (perimorphose)
Kobberelv. Brownred crystals on up to 2 cm in a tunnel for a powerplant.
Other locations

Iceland. A common zeolite.
Poona, India.

To silicate index.
Mineral group index.
Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.

axelsson@acc.umu.se

To my homepage.
Last changed : 1998-03-07

Mineral class	Silicates : Tekto silicates : Zeolites
Chemical formula	CaAl₂Si₇O₁₈6H₂O (Mineral i Sverige) CaAl₂Si₇O₁₈7H₂O (Mineraler, stenar och ädelstenar) (Ca,Na₂,K₂)[Al₂Si₇O₁₈]7H₂O (Mineraler och bergarter) NaCa₂Al₅Si₁₃O₃₆14H₂O (Norsk steinbok) (Bergarter, mineral, fossil) (There seems to be some difference between books about the chemical formula)
Crystal system	Monocline
Habitus	Prismatic crystals, often as leaf formed crystals of twins or fibric radiating aggregates.
Cleavage	One complete cleavage. Uneven fracture.
Hardness	3.5-4
Density	2.1
Color	White, yellow, grey to reddish brown. Often translucent.
Streak	White.
Luster	Glas to pearly.
Description
Occurance	Oftly created in cavities in basaltic rocks. More seldom in methamorphic rocks.
Associates	Heulandite.
Notes	All zeolites are soluble in strong hydrocloric acid when powdered, leaves silicagel as a rest. The water is driven out when heated. Melted by a micro flame.
Locations	Not so common in Sweden. Fröå mine, Åreskutan, Jämtland. As drusy fillings in cracks together with chabasite. Fridhems mine, Gällivare. Common together with chabasite in drusy goldbearing quartz. Malmberget iron mine, Gällivare. As yellow round aggregates together with chabasite in holes in metabasite and scarn. Svappavaara mine. As in Malmberget. The most common zeolite mineral of Norway. Gjörvik, in a big quarry. In cracks and holes in a gneiss. Together with chabasite. Vestlandet. A very common mineral here, found in most roadcuttings and tunnels together with laumontite and calsite. For example in : Dale (railwaytunnel), tunnels and roads at Hellesylt, Geiranger-Norddal and Gurksköy. Svenningsdal. Crystal masses of stilbite fills out the room after calcite crystals. (perimorphose) Kobberelv. Brownred crystals on up to 2 cm in a tunnel for a powerplant. Other locations Iceland. A common zeolite. Poona, India.