Tabular Sanidine crystal embedded in Trachyte

3D ModelNoAI

Locality: Siebengebirge, Cologne (Germany)

No.: 6034

Size: 7.5 x 6.4 x 1.8 cm

Formula: K(AlSi3O8)

Type: Igneous extrusive (volcanic) rock

Description: The extrusive, aphanitic, often porphyritic, equivalent of syenite, composed mainly of alkali feldspar and minor mafic minerals (biotite, hornblende, or pyroxene). As there are two principal groups of syenite, there are likewise two groups of trachyte: alkali trachyte and calc-alkali trachyte. (Gk. trachys, rough; from its rough appearance).

In this specimen, the tabular crystal of Sanidine is embedded in Trachyte matrix showing the typical striations.

Essential minerals: alkali feldspar, biotite, pyroxene, amphibole, (± plagioclase less than 10% of the total feldspar).

Accessory minerals: zircon, titanite, apatite, etc.

Website: http://geology.uaic.ro/muzee/mineralogie/

Concept & 3D-modelling by dr. Andrei Ionut APOPEI