High grade molybdenite mineralization

Virtual Museum ID: 19-NC-05

Specimen Summary

Many North American Mo deposits feature what is called “Brain Rock” or crenulated unidirectional solidification textures (UST) and which usually consists of parallel, closely spaced, <1cm quartz bands in a feldspathic matrix. This specimen features bands of molybdenite instead of quartz and is thought to be one of the few known examples of this style of Mo mineralization.

Specimen Data


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Collection Details

Original Collection:

Smithers Exploration Group (SEG)

Sub Collection:


Collection ID:


Virtual Museum ID:



Date Added to VM:


Location Information

Sample Origin:

Alice Arm, B.C.

Specific Site:

Roundy Creek deposit

UTM Easting:


UTM Northing:



09 (NAD 83)

Coordinate Accuracy:

Specimen Details

VM Category:


Primary Features:

High grade molybdenite mineralization

Primary Mineral Formula:

Primary Category:


Secondary Features:


Advanced Geological Information


The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.

Geological Formation:

Bowser Lake Group

Geological Period:

Middle Jurassic to Upper Cretaceous

Stratigraphic Age:

Geological Belt:

Stikine, Bowser Lake

Geological Terrane:


Minfile ID:

103P 113

Site Details:

The Roundy Creek deposit is located about 6.0 kilometres south of Alice Arm. This deposit has been extensively explored in the past for its molybdenum mineralization, resulting in the definition of several zones containing moderate reserves.

The deposit consists of a small elongate sheet-like Eocene quartz monzonite stock of the Alice Arm Plutonic Suite that intrudes a folded sequence of Middle Jurassic to Upper Cretaceous Bowser Lake Group argillite and greywacke. The enclosing sediments have been metamorphosed to biotite hornfels for about 200 metres outward from the stock. These rocks are all cut by narrow, northeast striking, steeply dipping hornblende and biotite lamprophyre dikes.

The stock is made up of a core of leucocratic quartz-eye porphyritic quartz monzonite that grades outwards into a shell of biotite quartz monzonite. It is cut by irregular masses and dikes of alaskite and is segmented by several northwest-striking faults along, and adjacent to, Roundy Creek. A potassic alteration zone of abundant sericite and biotite-coated fractures are developed in the stock. This zone occurs within and marginal to higher grade molybdenite mineralization.

The stock hosts three lens-like zones of molybdenite mineralization. An eastern zone contains uniform grades of molybdenite which occurs as selvages in numerous randomly orientated quartz veinlets and as fracture infillings.

Along and south of Sunshine Creek, a tributary of Roundy Creek, alaskite hosts bands and rosettes of molybdenite in the central and southern portions of the stock. The bands are 1 to 2 centimetres wide and the uniformly distributed rosettes are 1.0 centimetre in diameter.

In addition, molybdenite occurs in randomly oriented fractures with chlorite, and in closely spaced 0.5 to 1.0 centimetre wide quartz veinlets in alaskite and quartz-eye porphyritic quartz monzonite.

Indicated reserves at Roundy Creek are 7.0 million tonnes grading 0.06 per cent molybdenum (grade given was 0.11 per cent MoS2); indicated reserves at Sunshine Creek are 1.35 million tonnes grading 0.20 per cent molybdenum (grade given was 0.347 per cent MoS2); indicated reserves at High-Grade are 35,000 tonnes grading 0.40 per cent molybdenum (grade given was 0.668 per cent MoS2); conversion to Mo for all zones using a factor of 1.6681 (CIM Special Volume 15 (1976), page 467).

Avanti Mining Inc. released updated resources for the Roundy Creek property as part of a feasibility study for the Kitsault project (Avanti Mining Inc. News Release February 5, 2013):


Sunshine and Sunlight Area Tonnage Mo

Category (million tonnes) per cent

Indicated 1.94 0.109

Inferred 0.33 0.079

Roundy Area

Inferred 4.32 0.073

(0.022 per cent Mo cut-off)


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