Cínovec-Východ: the Definition of Sn, W and Li Ore Reserves in the Foreland of the Cínovec-Jih Deposit

Type of project:  Private project

Investor:  GEOMET s.r.o., Brno

Implementation period:  2014

Activities:

• Research of archival data
• Completing of conditions of exploitability
• Calculation of prospected reserves of lithium and tin-tungsten ore according the Czech Mining Act No 44/1988

The aim was to define a new deposit of Sn, W and Li ores in the north-eastern extension of the existing deposit Cínovec-Jih B3123700, both usable for underground mining. In the same area exists the lithium ore deposit Cínovec-Odkaliště B3268300, represented by tailings from the processing plant of the former Rudné Doly State Enterprise. The evaluation of the deposit was based on archival data, without new technical and laboratory works.

The tin-tungsten and lithium mineralization in Cínovec is associated with shallow intrusive polylithionite-topaz granite of the Cínovec type on the Czech-Saxon border. The granite permeates the Teplice rhyolite body in an ellipse elongated along the north-south axis. Mineralized granite body has a length of about 1500 m (on the Czech side 1100 m) and a width of max. 400 m (in the middle section is narrowed down to 180 m). The contact of granite with rhyolite is often accompanied by coarse-grained pegmatite bands up to 4 m (“stockscheider”).

The endocontact tin-tungsten mineralization is represented by two basic types:

1. The system of quartz lodes placed consistently with the course of the intrusive contact, rarely also of steep quartz veins - the main object of historical mining (the former deposit of Cínovec-Starý Závod).

2. Mineralized greisen bodies in the basement of the classical vein system and in its depth continuation (Cínovec-Jih, Cínovec-Východ), locally also greisens bordering the vein system.

Polylithionite-topaz albite granites are mainly fine-grained on the contacts. Vertically change to medium-grained albite granites with irregular syenitic layers and schlieren-like albitites. Polylithionite-topaz granite pass locally also into porphyric microgranites, which remember some facies of the Preiselberg type granite. Deeper zone of the granite intrusion up to the depth 700-750 m consists of biotite microgranite and medium-grained granite with biotite admixture.

On the deposits of Cínovec-Východ and Cínovec-Jih, distinct types of W and Sn-Li mineralization overlap materially and partly genetically. According to the deposit model of the GEOMET Company, the ores were classified into one of three types:

• Granite ore is the predominant type, represented by more or less autometamorphosed granite of different grain size, increased zinnwaldite content and irregular cassiterite admixture. Granite ore constitute 88.2% of the total volume of the deposit.
• Greisen ores are fine to medium grained, with predominating cassiterite and zinnwaldite (polylithionite-siderophyllite). Tungsten component (wolframite, scheelite) is significantly suppressed. Within the deposit represent 11.7% of the volume.
• Vein ores include schematic all other petrographic types of mineralized rocks (quartz and feldspar veins, pegmatite, etc...); in the model represent only 0.1%.

According to Czech legislation (Mining Act No 44/1988), the reserves calculated on the Cínovec-Východ deposit are classified as “prospected”.

In total were in the Cínovec-Východ deposit calculated over 15 Mt of complex ore containing about 37 kilotonnes of lithium, 23 kt of tin and 1.7 kt of tungsten. From this amount, the exploitable reserves are less than 3 Mt containing nearly 10 kt of lithium, 7 kt of tin and 1 kt of tungsten. The average metal content is 0.23% Li, 0.15% Sn and 0.010% W.

From the results of the work suggest the following recommendations:

• Implementation of new technical works in order to verify the content of all commercial components in the ore and the possibility of their treatability.
• Reassessment of the other sectors of the Cínovec Ore District according to new economic conditions. Primarily the Cínovec-Jih deposit, where are currently reported only non-extractable reserves.