Category: Uncategorized
March 18, 2004

News Release: American Bonanza Drills High Grade Gold In The Surface Drilling Program At Copperstone

AMERICAN BONANZA GOLD MINING CORP. (TSX Venture: BZA) ('Bonanza') is pleased to report positive drill results from the surface drilling program at the 100% owned Copperstone Project in Arizona. The surface drilling program is designed to conduct exploration and provide data for resource estimation, with the goal of producing a measured resource in and around the D-Zone and the C-Zone.

The surface drilling program has begun to the north of the open pit, Southeast of the C-Zone, and approximately 1,000 feet Southeast of the D-Zone, which is currently the subject of a detailed underground drilling program. The first hole in the surface drilling program encountered a 13 foot (4.0 metre) interval grading 0.77 ounces of gold per ton (26.5 grams per tonne gold) with 0.5% copper. The following table is a summary of the assay results for the first drill hole from the surface drilling program; the hole was drilled on a 180 azimuth (due south):
Drill Hole Dip From - To Interval Gold Gold Copper
Hole Length (degrees) (feet) Length Grade Grade (%)
Number (feet) (feet) (opt) (g/t)
CRD-04-01 885 -82 814.5-827.5 13 0.77 26.5 0.5

The above result is very near the true thickness of the mineralised structure. CRD-04-01 was drilled with 720 feet of reverse circulation followed by 165 feet of core drilled at the bottom of the hole. The mineralised zone was encountered in core portion of the drill hole. Recoveries from the surface drilling program to date are excellent. While not drilled on a grid, the nearest drill hole to CRD-04-01 is approximately 140 feet distant with the nearest other drill holes being over 200 feet distant.

Drilling continues on the surface program to target the Copperstone fault with two drilling rigs currently working and additional rigs to be on site soon. CRD-04-01 is the first hole of a 30,000 metre surface drill program that will continue through most of 2004. Results from additional drill holes will be reported as they become available. All assays at Copperstone are at least triple-checked routinely.

Mr. Brian Kirwin, President and CEO stated: 'These very positive results over mineable widths are an encouraging indication of the potential of Copperstone to ultimately support a significant, low cost gold mine. It is important to note that this ore-grade intercept was discovered utilizing our geologic model. This model is constantly under revision as new information is gathered and serves us well as a predictive tool in our definition drilling program.'Additional information concerning this drill hole is available on the Company's website at: in the Copperstone page.


The Copperstone gold mineralization occurs within a package of sedimentary and volcanic rocks, in northwest striking, moderate to shallow dipping fault zones, principally the Copperstone Fault. Intensely sheared, altered and replaced rock characterizes the Copperstone Fault in the vicinity of the D-Zone. Alteration consisting of intense hematite and magnetite replacement, chloritization and silicification has been observed in the Copperstone Fault underground and is consistent with alteration visible in previous drilling.

Gold mineralization is restricted to these fault zones, with little to no gold mineralization present in the wallrocks. Future exploration and development efforts will target these mineralized faults to follow up along strike and dip from the current results and previously drilled mineralization.

Drilling services are being provided by an international drilling contractor, Layne Christensen Company of Chandler, Arizona. The drilling and assaying are conducted under the supervision of Gregory French, CPG #10708, a Qualified Person as defined in Canadian National Instrument 43-101.

The surface program core is HQ size, equaling 2.625 inches in diameter. The core samples are collected by Bonanza personnel at the drill for each drill hole. All of Bonanza's facilities are secure, inside the fenced compound. The core is transported to Bonanza's core processing facility on site at Copperstone by Bonanza personnel.

The core is then logged for recovery and other geotechnical features, prior to being sawed lengthwise in half by Bonanza personnel. Individual core samples are selected on a geological basis to characterize the gold mineralization associated with various rock types, alteration types and structural horizons. Subsequent to sawing and sampling, the remaining half core is geologically logged and stored on site as reference samples.

Assay sample sizes average 5.5 pounds for the surface drilling. The core samples are bagged, labeled and tied at the Copperstone project site by Bonanza personnel. Geologic information is recorded on standardized sample description forms which included color, rock type, alteration, mineral species and abundance. Samples are stored in a secure facility at the Copperstone project site. Bonanza personnel transport the samples to America West Airlines'airfreight desk at the Lake Havasu City, Arizona airport.

America West Airlines transport the samples to the airport in Reno, Nevada. There, representatives of American Assay Laboratories (AAL) in Sparks, Nevada receive the samples and take custody of the samples. AAL is ISO / IEC 17025 certified and has successfully completed Canadian proficiency testing (CCRMP).

At the AAL laboratory, the core samples are dried, crushed to -10 mesh, pulverized to -150 mesh, split to 1,000 gram pulps, and fire assayed for gold three times using 2-assay ton fire assay charges with a gravimetric finish. Reported gold grades are the average of these three assays for each sample. A total of 52 core samples were assayed in triplicate for this hole. There is good correlation between the triplicate assays. All samples greater than 0.100 opt, standards, and blanks are routinely submitted to additional labs for verification. An additional routine 4 standards were inserted for assay for the drill hole announced here.

Check assays are routinely submitted to BSI-Inspectorate, Sparks, NV and Chemex Labs, Sparks, NV for 2- or 5-assay ton gold analysis. Both labs are ISO 9002 certified. Bonanza personnel deliver the samples to the check labs.

Additional information about Bonanza can be obtained at:

AMERICAN BONANZA GOLD MINING CORP. (signed) Brian Kirwin President and Chief Executive Officer

Giulio T. Bonifacio Executive Vice President and Chief Financial Officer (604) 688-7523

NEWS RELEASE TRANSMITTED BY CCNMatthews The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this news release.

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