Lened Emerald Study (Project Leader: Hendrik Falck)

In July 2002, a short field campaign was conducted to examine the Lened Emerald Showing 50 km north of the Cantung Mine in the Selwyn Mountains. The researchers included Lee Groat, Dawn Kellet (UBC), Dan Marshall, Lesley Meston (SFU), and Hendrik Falck (C.S.Lord). The Lened property has seen extensive investigation of a tungsten skarn deposit, but it was not until 1997 that Ron Berdahl discovered that the property also hosted an emerald showing. The focus of this study was to identify the setting for the emeralds at the property and then determine possible formational mechanisms to account for the showing. This also entailed the examination of the nearby intrusions as potential sources of beryl.

The emeralds are hosted in a small, skarn-altered limestone lens east of the main tungsten showing. The location of the skarn appears to have been controlled by a fault that also forms the contact zone between a large package of pyritic black shales and the rhythmically-bedded limestone host of the skarn. The fault shows a brittle brecciation phase followed by an extensive fluid alteration overprint. The 100 x 20 metre skarn lens is cut by at least 35 significant quartz veins of which approximately 80% contain green beryl. The beryl crystals found were generally too pale and small to be of economic quality, but there was a high proportion of clear gemmy crystals.

The setting of the skarn, in fault contact with black shales and in proximity to a granitoid intrusion, is not uncommon in this part of the Cordillera. With the ordinariness of this setting, the discovery of more, and possibly better quality emeralds is largely a factor of the amount of prospecting. Now that the setting has been described, prospectors can keep this model in mind during their travels. With any luck , the green gems will not remain an anecdotal oddity in the Canadian North for long.