Large-scale Lithium Pegmatites Intersected at Ringwood
- Broad drill intersections above 0.1% Li2O in pegmatites up to 150m true width encountered in first RC drilling at the Ringwood Prospect in the NT.
- Core's activity at Ringwood is the first recorded exploration on the virgin lithium pegmatite discovery at Ringwood.
- Drilling confirms Mastotermes Pegmatite Target is up to 200m wide, at least 140m deep and has potential for economic lithium grades over 1,300m length.
- Drilling confirms the widespread and abundant distribution of pegmatite dykes over a 4km long and over 2km wide area.
- Majority of the large area Ringwood Prospect is yet to be tested by RAB and RC drilling.
- Recent Ground Penetrating Radar surveys in conjunction with magnetics and soil data have highlighted more pegmatite targets for testing.
- Second phase of shallow drilling to commences this month to continue exploration for spodumene mineralised pegmatite at Ringwood.
Three separate drill traverses intercepted broad zones anomalous in lithium and grading over 0.1% Li2O, giving great encouragement to the potential of lithium mineralising processes at the Ringwood Pegmatite Swarm.
Core's recent drilling has confirmed numerous large pegmatite bodies widespread throughout the Ringwood Prospect. Ringwood covers a large area, more than 4km long and over 2km wide representing a significant volume of pegmatite with elevated lithium content.
The better intersection in RC drilling to date at Ringwood include:
- RRC010, 21m@ 0.16% Li2O from 92m
- RRC012, 52m @ 0.14 % Li2O from 90m
- RRC013, 21m @ 0.10 % Li2O from 58m
- RRC014, 46m @ 0.13% Li2O from 78m
Given the very large area of the Ringwood Prospect and the abundant number of pegmatites intersected in 27 of the 35 RC holes, there is substantial potential for numerous lithium pegmatite targets at Ringwood.
Mastotermes Pegmatite Target
Core's first RAB and subsequent RC drill traverse at the Mastotermes pegmatite target has discovered and defined a pegmatite up to 200m wide, down to at least 140m depth at the northern end of a 1,300m long magnetic feature (average density of pegmatite is approximately 2.7 g/m3).
Broad intersections of highly anomalous lithium were recorded in drill holes RRC010 and RRC012 at Mastotermes. RRC012 intersected 52m (90-142m end of hole) of pegmatite averaging 0.14% Li2O and on the same traverse RRC010 intersected 21 metres (92-113) pegmatite averaging 0.16% Li2O.
Core initially conducted 3 Ground Penetrating Radar (GPR) traverses across various pegmatite targets at Ringwood. GPR is working particularly well at Ringwood given the large scale of the pegmatite bodies and their strong response.
The significant GPR anomaly at Mastotermes corresponds well with the related magnetic feature in both scale and location and the first RC drilling traverse 500m to the North-East (see Figures 1-3 in the link below).
Core is planning a number of RAB drill traverses across Mastotermes to test and define the extent of the 1,500m pegmatite target (see Figure 3 in the link below).
Once the shallow RAB drilling is completed, a second phase of RC drilling is planned on Mastotermes to test for internal lithium zoning within this very large pegmatite body.
Ringwood Prospect - Phase 1 RC Drilling
The initial RC program at Ringwood comprised 35 RC holes (RRC001 to RRC035, total 4,886m) to test the numerous pegmatites detected by the first RAB program.
Core's first drilling has discovered very large pegmatite bodies like Mastotermes within the greater Ringwood area, but only a small proportion of the pegmatites targets at Ringwood have been drilled in this initial program (see Figure 4 in the link below).
The drill traverses at Ringwood discovered over 20 large pegmatites with widths ranging from 10m to 150m (true thickness) and with strike lengths to range 100m to 1,300m interpreted from magnetics.
The numerous intersections of elevated lithium, especially at the three best traverses, are interpreted to be significant indicators of lithium fertility of the Ringwood Pegmatite Swarm.
In general, the pegmatites are vertical and strike northerly to north-easterly. Inspection of RC chips has shown the pegmatites to comprise coarse grained quartz, feldspar and muscovite.
The mineralogy of the pegmatite bodies is variable and it was common to intersect quartz veins, tourmaline enriched pegmatite and quartz-muscovite veins that range 20cm to 1m. The notable yellow colouration of pegmatite caused by epidote alteration was encountered in many of the drilled pegmatites and was strongest in the rubidium enriched pegmatite interval in RRC019. Mineral and alteration zonation are characteristics of lithium bearing spodumene pegmatites.
At Ringwood, the pegmatite dykes are predominantly orientated parallel to the regional fabric associated with northerly orientated fold axes in the surrounding metasediments of the Burrell Creek Formation. In detail, each pegmatite may follow the foliation evident in the magnetics images, but also diverge at an angle or cross cut the prevailing country rock foliation and sedimentary layering as with Mastotermes.
The extensive sheet of thin cover sediments and minimal outcrop, combined with large size of the Ringwood prospect and the sparse drill coverage to date has made it challenging to interpret alteration and mineralisation zonation.
Next Steps at Ringwood
Shallow RAB drilling is expected to re-commence at Ringwood in September to initially follow up the newly discovered lithium enriched pegmatites.
RAB is also planned to explore for pegmatite concealed beneath shallow laterite and soil cover and to test features interpreted from the GPR traverses, magnetics and soils.
Deeper RC drilling is planned to follow-up prioritised pegmatite targets that are defined at Ringwood in due course.
To view tables and figures, please visit:
About Core Exploration Ltd
Core Exploration Ltd (ASX:CXO) is an emerging lithium producer focused on development of its Finniss Project near Darwin in the Northern Territory. Core owns 100% of Finniss, a major developing project that lies close to existing infrastructure such as the Darwin Port, grid power, gas and rail infrastructure.
The Finniss Project covers a 500km2 tenement holding and 25 historic pegmatite mines. The project area is about 80km from Darwin Port. Exploration work has generated a near term development timeline, with feasibility studies to be completed over the course of 2018 ahead of receipt of approvals in early 2019 and planned first production during 2019.
An aggressive exploration program is under way, which has confirmed the high quality prospectivity across much of the Finniss Project area. Core's stated ambition is to upgrade Finniss' resource base to fast-track commercialisation options.
Core Exploration Ltd