|Zeolites and other Minerals from La Gomera, Canary Islands
A collectors perspective
by Volker Betz
from La Gomera have been first collected in 1987 by the author. The
presence of zeolites is not surprizing in the given geological
environment. (Rothe, 1996) . In 1987 the locations Number 3,4,5,6,7
have been recognized. A first paper about zeolites on La Gomera was
presented by TERNES (1992) describing the location of Mareantes 2 km E
of Hermigua. This is by far the best zeolite location on the island. At
a later visit in 1995 additional to the species mentioned by TERNES
Apophyllite was found. Of other minerals the Augite from location 6 is
|Home||1 2 3 4 5 6 7 8 9 10
|1. and 2. Mareantes and Playa de Caleta E of Hermigua|
E of the Playa de Hermigua are ruins of a former Banana harbor. Near to the partially destroyed road to that harbor and at the N-Slopes of the Marenates hill, zeolites are abundant. The paragenesis consists of Analcime lining the cavities in small crystals followed by Thomsonite in fan-shaped aggregates of bladed crystals and Natrolite/Mesolite needles often in oriented intergrowths with the Thomsonite. Also present is Chabasite in crystals of a few mm. In the tide zone, which can be accessed only at very smooth sea, pockets in a dark basalt are lined with Analcime followed by Natrolite/Mesolite needles, Thomsonite , Apophyllite (up to 7 mm). and Calcite.
Left: Mesolite/Natrolite Needles with Thomsonite 6x5 cm
Top: Thomsonite crystal ca. 2 mm
Left: Mesolite/Ntarolite with Thomsonite ca. 3x5 mm
Down left: Apophyllite and Calcite on Analcime ca. 6x9 cm
Down: Thomsonite ca. 3x4 mm
Apophyllite on Natrolite ca. 4 mm.
Left: Apophyllit xl ca. 7 mm on Analcime
|3. and 4. Roadcut S Hermigua and road junction near El Rejo|
S of Hermigua the road leads in several sepentines to the junction near El Rejo. The Basatlic Rock along the road shows cavities with Analcime, Natrolite/Mesolite and Calcite. Direct at the road juction the rock contains nice Crystals of Augite and some Analcime, Thomsonite and Natrolite/ Mesolite similar to the location E of Hermigua.
Above: Augite Crystal 15x15 mm from El Rejo. Left: Analcime 4x5 cm from roadcut S of Hermigua.
|Above: Analcime crystals 3 mm from roadcut S of Hermigua -Left: Calcite, 15 mm on Natrolite from roadcut S of Hermigua|
|5. Foot-Trail E Embalse Benchijichigua|
|Above left: Thomsonite and
Phillipsite ca. 1-2 mm
Above : Hemispheres of Thomsonite and Chabasite
Left : Model-like Chabasite-twins
One of the popular walking tracks of Gomera starts at about 1000 m near the Roque de Agando leading south, down to Playa de Santiago. E of the Embalse de Benchijigua and near the track zeolites are abundant. Beside some calcite, small crystals of Phillipsite, Chabasite and hemispheres thomsonite are present. The lining of the cavities are very minute analcime-crystals.
Below: Phillipsite from Benchijigua ca 1.5 mm
| 6. Car Track to
Erque E of Fortaleza
2km NE of Fortaleza, the remakable table-mountain at SW-Gomera, a car track descends down to the Barranco der Erque. About in the middle between the two first U-turns a yellow brown tuff is exposed to the surface. This tuff is very rich in fine Augite Crystals up to about 2-3 cm. Fine crystals can be easy collected from the surface or broken from the soft rock . Matrix specimen are difficult to get.
Above: Augite Twin after (100) 22mm
Above: Augite Crystal-Cluster 25 mm
Left: Augite Crystal 12 mm in Tuff
|7. Roadcut E of La Dama|
|E of La Dama a small road leads to
La Rajita, a closed Fish-Factory at a small gravel beach,
the Playa de La Rajita. A few hundred NNW of La
Dama the road crosses a vesicular lava of which the
cavities are covered by Spherules of Carbonates (Calcite
?). Beside the Carbonates very small Phillipsite and
Chabasite crystals are also present.
Left : Calcite spheres fom La Dama. Specimen is 9 cm wide.
Montain Track Valle Gran Rey
Around the Valley Gran Rey several mountain paths allow hiking in the butyful screnery. At the estern slopes small Phillipsite and Chabasite have been found.
At the small harbor the vesicules in the rock are coated with flat Calcite rhomboedrons.
|10. Roadcut NE of Epina|
|Altered rock near the road, about in the middle between Alojera and Eipna, contains vesicules with larger Calcite Scalenohedrons (above 6x8 cm)and fibrous Mordenite.||Above : Calcite with Mordenite, 3x5 cm|
Rothe P.(1996) Kanarische Inseln (Sammlung Geologischer Führer 81) -2. Auflage 307 pp Berlin, Stuttagart
Ternes B. (1992) Mineralfundstellen aud der Kanareninsel Gomera - Lapis 17, 42-45