Davenport Resources Ltd non-executive director (then chairman) Patrick McManus speaks to Proactive Investors about our South Harz Potash Project in central Germany.
South Harz, Germany
Map of licence location
The South Harz Potash District, located in the heart of Germany, was one of the world’s most important Muriate of Potash (MOP) producing regions, with a history of mining going back over 120 years. Prior to the re-unification of Germany in the 1990’s, the former German Democratic Republic produced approximately 3.3 million tonnes of K 2 O annually from mines within and around the South Harz Potash District. Historically, both Sylvinite and Carnallitite potash ores have been mined in the South Harz Potash District by conventional underground room and pillar mining. More recently Carnallitite ores is being mined by modern day solution mining techniques, at a production rate estimated at just over 100,000 tonnes MOP per year. It is the belief of Davenport Resources that targeted and strategic investment in the South Harz Potash District of Germany can support modern day potash production rates similar to those of former times.
Davenport’s South Harz Project comprises three perpetual mining licences, Ebeleben, Mühlhausen-Nohra and Ohmgebirge and two exploration licences, Küllstedt and Gräfentonna, covering a total area of approximately 659km² in Germany. Davenport’s licences surround five former underground potash mines that were closed down after German reunification in the 1990’s. Production from these five mines is estimated as 181.7 million tonnes of potash produced since the 1890’s. The three perpetual mining licence areas and the exploration licence area Küllstedt have been extensively explored for Potash by the former GDR and a vast database of drillholes and technical studies exists to support the geological model. The Gräfentonna licence was extensively explored for Hydrocarbons, and much of the existing exploration data is useful for the evaluation of potash.
At the time of closure in 1991, the Volkenroda mine was scheduled to be extended to the east into the Ebeleben Mining Licence area, and shaft sinking for a new ventilation shaft had begun and was at an advanced stage. Similarly, investigations were well underway to extend the Volkenroda mine to the west, or to establish a new stand-alone mining operation within Mühlhausen-Nohra Mining Licence area currently held by Davenport Resources.
Davenport JORC 2012 Resources
Davenport’s three perpetual mining licences in Germany, Ebeleben, Mühlhausen-Nohra and Ohmgebirge, are unique and valuable. Over the past year Davenport Resources has focused work on evaluating the vast archive of exploration data with the aim of defining JORC 2012 compliant.
Inferred resource estimate of 557 million tonnes grading 12.1% K2O was announced in April 2018. Following on, Davenport Resources continued to expand its resources base, and in October 2018, the company announced the Mühlhausen-Keula sub-area Inferred Resource of 1.13 billion tonnes grading on average 11.1% K2O. In November 2018, Davenport Resources released details of resource modelling work from its Nohra-Elende Sub-Area and released a JORC 2012 Inferred resource of 1,698 million tonnes grading 9.7% K2O. Additionally, Davenport’s consultants Micon International, identified a further portion of the Nohra-Elende sub-area as an Exploration Target where the drill spacing was too great to determine an Inferred resource. Details of this exploration target were announced on 15th January 2019 for a target of 638 to 1,162 million tonnes grading at 9.2 – 11.1 % K2O*.
Davenport now controls over 3.4 billion tonnes (grading 10.5% K2O) of JORC Inferred Resource, including 1.2 billion tonnes Sylvinite grading 13.2% K2O. Total contained K2O for the Ebeleben and Mühlhausen-Nohra Mining Licences now exceeds 358 million tonnes.
Seam |
Tonnage (Mt) |
K2O (%) |
K2O (MT) |
|---|---|---|---|
| Sylvinite | 324.0 | 15.6 | 50.4 |
| Carnallitite | 252.6 | 7.5 | 18.9 |
| Total Ebeleben | 576.6 | 12.1 | 69.3 |
| Sylvinite | 834.3 | 12.1 | 100.7 |
| Carnallitite | 295.8 | 8.2 | 24.2 |
| Total Mühlhausen-Keula | 1,130 | 11.1 | 124.9 |
| Sylvinite | 101.0 | 14.2 | 14.0 |
| Carnallitite | 1,597 | 9.41 | 150.0 |
| Total Nohra-Elende | 1,698 | 9.69 | 165.0 |
Total Davenport JORC Inferred Resources (Nov 2018) |
3,405 |
10.5 |
358.8 |
Table 1. Davenport Inferred Resources (JORC 2012) – Ebeleben and Mühlhausen-Nohra Mining Licences (including Mühlhausen-Keula and Nohra-Elende sub-areas)
Seam |
JORC Category |
Tonnage (Mt) |
K2O (%) |
K2O (MT) |
|||
|---|---|---|---|---|---|---|---|
Minimum |
Maximum |
Minimum |
Maximum |
Minimum |
Maximum |
||
| Upper Sylvinite | Exploration Target | 179 | 223 | 11.0 | 13.5 | 22 | 27 |
| Carnallitite | Exploration Target | 459 | 939 | 8.5 | 10.5 | 44 | 89 |
Total Nohra-Elende Sub-Area |
Exploration Target (Jan 2019) |
638 |
1,162 |
9.20 |
11.07 |
66 |
117 |
Table 2. Davenport Exploration Target (JORC 2012) – Nohra-Elende sub-area, part of the Mühlhausen-Nohra Mining Licence*
*The potential quantity and grade of the Exploration Target is conceptual in nature, there has been insufficient exploration to estimate a mineral resource and it is uncertain if further exploration will result in the estimation of a mineral resource.
Geological Setting
The project lies within the Thuringian Basin that contains a potash-rich evaporite sequence of Permian age. The potash deposits were formed in the Zechstein Sea, a shallow salty body of water that covered a large area extending from the north of England, to central Poland, and eastern France. The so-called Zechstein evaporites, which developed at the margins of the Zechstein Sea, have historically been an important source of salts, potassium fertilisers and hydrocarbons in the entire region. The geology that controls the South Harz Potash seams is the same geological units that contains Sirius Minerals’ Woodsmith Mine and ICL’s Boulby Mine in North Yorkshire and K+S’s potash mines located in the central and western parts of Germany. Due to the extensive mining and exploration history in the area, the geology of the project area and potash mineralisation is reasonably well known. The evaporite sequence containing the potash seams within the South Harz area occur at depths of between 500m and 1,200m below surface. The overlying rocks consist of a marine sequence of sandstones, mudstones, marl, dolomite and siltstones.
Within the Küllstedt licence the potash mineralisation is hosted by the Permian Stassfurt Formation which ranges in thickness between 32m and 255m. Within the Stassfurt Formation, the Kalifloez Stassfurt unit (z2KSt) contains the potash seam which underlies the entire Küllstedt licence area. The potash unit is up to 58 metres thick and appears to be richer in Carnallite potash mineralisation in the north and Sylvite mineralisation in the south. The base of the Stassfurt Formation is a dolomite unit (z2D) that has been of interest to hydrocarbon explorers in the past.
Exploration Potential
Küllstedt Exploration Licence
Past mining and exploration within the Küllstedt exploration licence has included three vertical shafts which operated up to 1924 (excised from the tenement), as well as potash exploration drill holes and hydrocarbon wells that have drilled through the potash formations of interest. Geological data and assay data for the drill holes has been used to develop a 3D geological model of the potash seam. An Exploration Target for potash within the Küllstedt licence is 4,055 million tonnes to 5,141 million tonnes with a grade ranging between 7.2% K2O and 25% K2O, (Davenport Resources replacement Prospectus p30, 19 Jan 2017*).
Licence Area |
JORC Category |
Tonnage (Mt) |
K2O (%) |
K2O (MT) |
|||
|---|---|---|---|---|---|---|---|
Minimum |
Maximum |
Minimum |
Maximum |
Minimum |
Maximum |
||
| Küllstedt | Exploration Target | 4,055 | 5,141 | 7.2 | 25.0 | 292 | 1,285 |
Table 3. Davenport Resources Exploration Target (JORC 2012) – Küllstedt Exploration Licence (March 2015)*
*The potential quantity and grade of the Exploration Target is conceptual in nature, there has been insufficient exploration to estimate a mineral resource and it is uncertain if further exploration will result in the estimation of a mineral resource.
Gräfentonna Exploration Licence
Although less geological information is available on the Gräfentonna licence, the stratigraphy is broadly similar to the Küllstedt licence, and more importantly the Ebeleben Mining Licence. Based on preliminary data the Gräfentonna Licence shows a sylvinite-dominated seam running down the central part of the licence area and carnallitite-dominated seam towards the eastern side of the licence.
A detailed geological review and geological model of the potash seam underlying the Gräfentonna licence using the available drilling and geological information has allowed an Exploration Target to be calculated of between 2,678 and 3,396 million tonnes grading between 4.3% and 25% K2O (ASX release 22 May 2017*).
Licence Area |
JORC Category |
Tonnage (Mt) |
K2O (%) |
K2O (MT) |
|||
|---|---|---|---|---|---|---|---|
Minimum |
Maximum |
Minimum |
Maximum |
Minimum |
Maximum |
||
| Gräfentonna | Exploration Target | 2,678 | 3,396 | 4.3 | 25.0 | 115 | 849 |
Table 4. Davenport Exploration Target (JORC 2012) – Gräfentonna Exploration Licence (May 2017)*
*The potential quantity and grade of the Exploration Target is conceptual in nature, there has been insufficient exploration to estimate a mineral resource and it is uncertain if further exploration will result in the estimation of a mineral resource.
Planned Exploration of Germany
A review of JORC Inferred resources contained within Davenport’s perpetual mining licence areas has highlighted several areas that have the potential size and grade to warrant investigation into a new stand-alone potash mine. These areas include the entire Ebeleben Mining Licence, which is rich in high grade Sylvinite, the northern part of the Mühlhausen-Nohra Mining Licence, which contains extremely thick Carnallitite and Kieserite, and the southern portion of the Mühlhausen-Nohra Mining Licence, extending into the southern portion of Davenport’s Küllstedt Exploration Licence, where the underground geology contains thick seams containing high grade sylvinite together with valuable sulphate minerals. In conjunction with its consultants, Davenport Resources has decided that the Mühlhausen-Nohra and Küllstedt Licences should become the focus for further evaluation drilling and an economic study during 2019.
The next phase of the exploration program is to drill confirmation holes on the Küllstedt licence thus twinning existing exploration holes that have previously intersected potash. This will allow validation of detailed information from past exploration campaigns with the aim of upgrading the existing Exploration Target on the Küllstedt licence and parts of the existing JORC Inferred Resources on the Mühlhausen-Nohra Mining Licence to JORC-compliant Indicated Resources. Davenport is working with the regional mining authority to meet the requirements to obtain approval to commence drilling.
