Name: Marigold mine.

Location: The mine is located in Humboldt County, Nevada, in the US, on the Battle Mountain-Eureka trend.

Controlling Company: SSR Mining (formerly Silver Standard).

Brief Description: Marigold is a large run-of-mine heap-leach operation with several openpits.

Brief History: The mine has been operating since 1988.

The first recorded gold production from the property occurred in 1938, when the Marigold Mining Company (Unionville) developed and operated an underground mine, which came to be known as Marigold.

In 1943, Horton’s estate sold its interest in the property and claims. Several unsuccessful attempts to open and operate the mine were made before exploration activities began in 1968.

From 1968 to 1985, several companies conducted exploration programmes in the Marigold area, completing 126 exploratory drillholes.

In 1985, Vek/Andrus Associates drilled three holes under the supervision of Ralph Roberts in the Section 8 area of the property, north-east of the old underground mine. Encouraged by the deep level of oxidation, the presence of favorable rock units, anomalous indicator elements and anomalous gold values, exploration consortium Cordex leased the Vek/Andrus Associates claim block in September 1985 and began a drilling programme in November of the same year. This resulted in the discovery of the 8 South deposit.

Following further drilling in the 8 South deposit in 1986, a joint venture was formed between SFP Minerals Corporation and the Cordex group, which consolidated some of the land holdings over the Marigold area. Later in 1986, the Cordex group leased certain other claims, including the historic Marigold mine, Top Zone, East Hill and the Red Rock area from various claim holders.

In March 1988, a production decision was made on the 8 South deposit by Rayrock Mines, then the operating company of Cordex. By September 1988, Rayrock began stripping on the 8 South pit and in August 1989 the first gold doré bar was poured at the Marigold mill.

In 1994, mining of the 8 South deposit was completed and the Marigold mill was no longer used for processing ore, with Marigold becoming a run-of-mine heap-leach operation. In the same year, the Basalt, Antler and Target II deposits were discovered at the southern end of the property in the “checkerboard” square known as Section 31.

In March 1999, Glamis Gold acquired all Rayrock’s assets, resulting in Glamis Gold holding a two-thirds interest in Marigold. Homesake Mining Company, which had been acquired by Barrick Gold in 2001, held the remaining one-third interest in the mine.

In 2007, discovery holes were drilled in the Red Dot deposit.

Silver Standard acquired the mine in April 2014.

As of August 1, 2017, Silver Standard is known officially as SSR Mining.

Products: Gold.

Geology/Mineralisation: Three packages of passive margin sedimentary Paleozoic rocks are present at Marigold – the Valmy formation and the Antler and Havallah sequences. These rocks host minable gold on the property. 

At Marigold, late Cretaceous narrow, or thin, porphyritic granodiorite to dacite dykes and sills are exposed in outcrop or by mining. These dykes generally intrude the stratigraphic package at high angles and are north-west-trending. 

Tertiary and quaternary alluvium with intercalated tuff horizons and occasional basalt flows covers two-thirds of the bedrock geology on the property. 

The deposits at Marigold have been described as a “distal-type sediment-hosted gold/silver deposit”, related to Cretaceous to Eocene magmatism.

The distribution of gold on the property is controlled by structure and stratigraphy. The general shape of the zones of mineralisation are tabular, and geometries and attitudes appear to mimic those of bedding. Mineralised pods dip moderately to shallowly to the west and become steeper in and adjacent to the north-east to north-west normal faults. Gold mineralisation is also concentrated at the intersection of these faults. 

Sulphide mineralisation at Marigold occurs in favourable horizons and structural locations within sedimentary host-rocks and is a mix of pyrite, arsenopyrite, free gold, and assorted auriferous sulphides. 

Oxide mineralisation was formed by the weathering of the sulphide mineralisation as uplift and erosion exposed the deposit to the near surface environment. Groundwater penetrated the Marigold deposits along fractures and faults, and over time, the sulphide minerals were oxidised. In the process of weathering, microscopic gold was liberated from sulphide material and deposited along with secondary minerals, such as limonite and other oxide materials, along fractures within the rocks.

Reserves: Total proven and probable reserves as at December 31, 2017, were estimated at 205.1-million tonnes grading 0.46 g/t gold.

Resources: Total measured and indicated resources, inclusive of reserves as at December 31, 2017, were estimated at 370-.2-million tonnes grading 0.46 g/t gold. Inferred mineral resources were estimated at 49.7-million tonnes grading 0.41 g/t gold.

Mining Method: Openpit.

Major Infrastructure and Equipment: Marigold has waste-rock stockpiles, leach pads, carbon absorption and processing facilities, and a gold refining facility.

Currently the mine uses a fleet of 290 t haul trucks and three loading units.

Prospects: Four new higher-grade mineralised centres have been defined since SSR Mining acquired the mine. Additionally, deep sulphide exploration drilling has confirmed the presence of permissive rock units at depth.

Contact: Investor relations.

Contact Details:         
SSR Mining
Tel +1 604 689 3846
Email invest@ssrmining.com
Website www.ssrmining.com