Fundamental Minerals

Sialic Minerals

Feldspars

Feldspathoids

Quartz

Femic Minerals

Spodumene

Accessory Minerals

Rare Accessory

Alteration Products

Microstructures

Rocks

Jacupiranga complex

Synnyrite

Synnyrite: A kalsilite syenite with a micropegmatitic texture composed of symplectic K-feldspar-kalsilite intergrowths with biotite, albite, minor aegirine-augite, titanite, apatite, fluorite, magnetite, garnet and alkali amphibole. Synnyrites were firstly found by A. Y. Zhidkov (1962,1963) within the Synnyr alkaline massif in northern Baikalian region (hence the name). Le Maitre et al., (2005).

Kalsilite-bearing plutonic rocks are extremely rare. They have been described in the Palaeozoic to Mesozoic ultrapotassic massifs of the Baikal-Stanovoi Rift, Siberia (Synnyr, Sakun, Murun, and Yaksha), in the small Rischorr complex of the giant and predominantly sodic Devonian Khibiny Massif, and in the Ordovician ultramafic Batbjerg intrusion of East Greenland.

Synnyr pluton
The largest Kalsilite-bearing plutons are confined to Baikal-Stanovoy rifting system and situated between metamorphic rocks of Pre-Cambrian and Early Cambrian ages. The Siberian massifs are epizonal, rhythmically layered massifs characterized by ultramafic and mafic rocks and often associated with carbonatites. In these massifs the synnyrites represent a small fraction of the massif volume, and are restricted to the upper layered series. Melano- and mesocratic rocks (mica pyroxenites, shonkinites, pulaskites) prevail within the lower series and the leucocratic ones (nepheline and pseudoleucite syenites, synnyrites) predominate within the upper series.

Fig.1: Structure of the Synnyr pluton with AB and CD geological sections. Modified from Zhidkov (1978).

The Synnyr pluton (Fig.1) is an oval-shaped body with 3D funnel like morphology, intruding into a sedimentary sequence of Cambrian limestone, conglomerate and sandstone and Palaeozoic granitoids. From core to the rim following succession of rocks occur in following order: alkaline syenite, pseudoleucite syenite, microcline pseudoleucite syenite and nepheline syenite. At the central part the oval-shaped stock (100 km²), is an igneous complex comprising trachyte and pyroxene-syenite (pulaskite). One of the varieties of pseudoleucite-bearing rocks is synnyrite, consisting of microcline and intergrowth of orthoclase, kalsilite and sometime nepheline. In the intergrowth, the ratio of K-feldspar to kalsilite (+/- nepheline) varies between 67 and 33 vol%. The K₂O content of these rocks may be as high as 18-20 wt%. The vol% of pseudoleucite may be as high as 50-60 %. During the final stage, dykes of tinguaite, shonkinite, camptonite and monchiquite were emplaced. Geological age dating determined through the Rb-Sr isotopic method from minerals of nepheline syenites yielded an age of 330 Ma.

Sample kindly given to me by F.Stoppa

Bibliography

• Panina, L., Sharygin, V., Proshenkin, I (1995): Synnyrites-New Complex Alumina-Potassic Raw Material. Shigen-Chishitsu, 45(252), 223-233.

Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)	Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)	Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)
Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 10x (Field of view = 2mm)	Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 10x (Field of view = 2mm)	Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 10x (Field of view = 2mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 2x (Field of view = 7mm)
Garnet (brown), pyroxene (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)	Garnet (brown), biotite (green) and feldspar (colorless). Synnyrite from Synnyr pluton. PPL image, 2x (Field of view = 7mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. PPL image, 10x (Field of view = 2mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 10x (Field of view = 2mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)
K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)	K-feldspar-kalsilite intergrowth. Synnyrite from Synnyr pluton. XPL image, 20x (Field of view = 1mm)