| RELEASED
ON BEHALF OF TERTIARY MINERALS PLC:
20 May 2002
TERTIARY'S LATEST DRILLING INCREASES GRADE BY 77P.C. AT ROSENDAL
TANTALUM PROJECT .
- Strike
Length Of Drill-Defined Pegmatite More Than Doubled To 500m
-
Larger Samples Give More Representative Grade Indication
-
Structure May Be Part Of Larger Dyke Swarm With Strike Length
Of At Least 2.5km
Latest drilling by AIM-listed Tertiary Minerals plc at its Rosendal
tantalum project in south-west Finland has returned grades from
the main pegmatite dyke which average 77p.c. higher than those from
previous drilling of the same structure by the Geological Survey
of Finland (GTK). The drilling programme also extended the drill-tested
strike length of the main pegmatite dyke from 200m to 500m. It remains
open at depth and along strike. Furthermore, initial indications
suggest the Rosendal dyke may be part of a swarm of dykes with a
similar structural trend having a combined strike length of some
2.5km, the company adds.
The latest drilling programme consisted of 14 diamond core holes
on eight sections 50m-100m apart. Better intersections include 1,275g/t
tantalum pentoxide over 3.0m, 589g/t over 10.6m, 541g/t over 9.1m,
439g/t over 8.0m and 241g/t over 20.2m. The weighted average tantalum
grade from intersections of the main pegmatite dyke was 346g/t compared
with 195g/t from the GTK's 1989 drilling programme.
Tertiary says the higher tantalum grades now reported probably reflect
the fact that the drill samples were significantly larger than the
earlier GTK samples - drill core diameter of 64mm as against 32mm
for GTK, giving a drill core weight per linear metre of 6.4kg against
1.1kg respectively.
"It is generally accepted that larger samples are likely to be more
representative of in situ grade", the company states. "Increased
grade in larger samples has been noted by other tantalum explorers
and by Tertiary with respect to the 350kg metallurgical sample from
Rosendal which averaged 620g/t tantalum pentoxide, 28p.c. higher
than the average grade of smaller adjacent channel samples".
The drilling programme forms part of the Phase 1 pre-feasibility
study on the Rosendal project and was undertaken in conjunction
with limited trenching. The objective of the programme was to infill
and extend the main tantalum-bearing pegmatite dyke. Trenching was
used initially, but because the geometry of the dyke was found to
be more complex at its western end and the overlying till at the
eastern end was waterlogged, this approach proved ineffective and
the drilling programme was extended to test for strike extensions.
The main pegmatite is generally thicker and higher grade in the
eastern half although some very high grades have been encountered
in narrow intersections in the west.
The pegmatite continues strongly under till cover on the most easterly
section drilled where a number of parallel tantalum-bearing dykes
have also been intersected.
The results of the Phase 1 drilling and prospecting will now be
used to calculate a revised resource estimate as part of the development
pre-feasibility study.
Meanwhile, Tertiary is undertaking further prospecting and mapping
to evaluate the additional resource potential of the company's surrounding
exploration licences. Early work is encouraging, it says, and a
number of rare-metal type pegmatite dykes similar to Rosendal have
been found, three of which contains visible tantalite.
FULL TABLE OF DRILLING RESULTS AVAILABLE ON REQUEST
Further Info: Patrick Cheetham, Tertiary Minerals. Tel: 01625-626203;
mob: 07767-458751
Ron Marshman/John Greenhalgh, City of London PR Ltd. Tel: 020-7628-5518
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