Aller au contenu
SGS logo SGS Geological Services

Composites

Overview

Composites are the regularized values used to represent mineralization along drillholes. They are created from mineralized intervals and store the averaged values for each composite interval, such as grade over a given length.

In practice, composites are one of the main inputs used for statistical analysis, plotting, and block model workflows. They are usually generated at a consistent support, but Genesis also provides other compositing methods when a fixed length is not appropriate.

A composite stores:

  • the drillhole name,
  • the tag associated with the interval,
  • the from and to depths,
  • centre, start, and end coordinates,
  • documented length,
  • projected thickness when needed,
  • variable values,
  • optional declusterization weight.

Composite sets

Composites are managed in sets, in the same way as mineralized intervals.

Composites Dialog List

  • A new project includes a Default composite set.
  • You can create as many sets as needed.
  • Only one set can be the current set at a time.
  • The current set is the one typically used by composite-based operations, reports, and downstream workflows.

Use clear set names that describe the purpose of the set, for example a domain name, element, or support length such as CU_5m.

Creating composites

Use Create > Create Composites… to generate composites.

Composites are created from:

  • the current mineralized interval set, and
  • the visible drillholes.

If you recreate composites in a set that already contains data, Genesis warns you before replacing the existing composites. If the current composite set is already used by variogram pairs, Genesis also warns that recreating the set will clear those pairs.

Compositing settings

The compositing dialog contains the creation parameters and also shows informational sections for dilution and capping currently in use.

The main settings are:

  • compositing mode,
  • minimum sample length,
  • target composite length,
  • minimum interval length,
  • rounding method for calculated-length composites,
  • any applicable dilution and capping status.

Compositing modes

Genesis provides five compositing modes.

Central

Creates one composite at the centre of each mineralized interval.

Use this mode when you want one representative composite per interval instead of a regular support.

Regular

Creates composites at the specified length.

Additional settings:

  • Minimum sample length: excludes analyzed portions shorter than the specified threshold.
  • Length of intervals: target composite length.
  • Minimum interval length: controls whether a short remainder at the end of an interval is kept as an additional composite.

Example: if an interval is 10 m long and you create 3 m composites, 1 m remains at the end. If the minimum interval length is set to 1 m or less, Genesis creates the extra composite; otherwise it does not.

By Bench

Creates composites by bench using the Default Grid.

This mode is useful when composites must match bench geometry rather than a fixed drillhole length. A minimum sample length can still be applied to exclude very short analyzed portions.

Calculated Length

Creates composites by adjusting the composite length so the mineralized interval is divided completely while staying as close as possible to the requested length.

Additional settings:

  • Length of intervals: desired target length.
  • Minimum interval length: controls the minimum acceptable remainder.
  • Round method: determines whether Genesis creates more or fewer composites when the requested length does not divide the interval exactly.

Available rounding methods:

  • Round Up: favors a larger number of shorter composites.
  • Round Down: favors a smaller number of longer composites.
  • Round Closest: chooses the result closest to the requested target length.

Example: for a 25 m interval and a target length of 10 m, Genesis can produce either 2 composites of 12.5 m or 3 composites of about 8.33 m.

  • Round Up produces 3 composites.
  • Round Down produces 2 composites.
  • Round Closest chooses whichever option is closer to 10 m.

Original Sample

Creates one composite for each assay interval found inside the selected mineralized intervals.

Use this mode when you want to preserve original sample support instead of regularizing it.

Modifying composite sets

Composite data is usually not edited directly interval by interval. To change a set, the usual approaches are:

  • recreate the set with different compositing parameters,
  • extract a new set from an existing set,
  • apply operations such as capping or declusterization,
  • export the set, edit it externally if required, then import it again.

Common set operations

Genesis provides several operations on existing composite sets.

  • Merge Set: combines selected sets into a new set.
  • Cap Set…: creates capped output using user-defined capping values for selected variables.
  • Copy: duplicates an existing set.
  • Subsets: create, edit, combine, subtract, intersect, and filter subsets.

Extracting composites

You can derive new composite sets from an existing set.

From Envelope

Creates a new set containing composites that fall inside one or more selected envelopes.

An option is available to tag the extracted composites using the selected envelope information.

From Not In Envelope

Creates a new set containing composites outside the selected envelope or envelopes.

From Tag

Creates one or more new sets by extracting composites according to tag values.

From Extent

Creates a new set by copying only the composites that fall within a specified X, Y, and Z extent.

Tagging composites

Tags can be assigned or updated from supporting project data.

Available commands include:

  • Tag By Table…: tags composites using an interval table or GIS-style dataset.
  • Tag By Envelope…: tags composites according to one or more envelopes.
  • Tag If Not In Envelope…: assigns a separate tag to composites that are outside the selected envelopes.

These tools are useful for domain assignment, filtering, and reporting.

Declusterization

Use Operation > Declusterize… to calculate a weight for each composite.

Genesis supports two declusterization methods:

  • By Cell: uses X, Y, and Z cell sizes.
  • By Intervals: assigns weights according to the number of composites in each interval.

Additional options include:

  • Normalize the weights so the total weight sums to 1.
  • Separate by tags to decluster each tag population independently.
  • Grouping by none, by holes, or by intervals.
  • Use only center when grouping is enabled.
  • Copy in variable to write the resulting weight into a selected variable.

Declusterization is primarily intended for statistical review and charting. It generates declusterization statistics in the composite log and can be used in declusterized histograms.

Viewing logs and data

For any composite set, you can:

  • open View… to review the composite table,
  • open View Log… to see how the set was created or processed.

The log is especially useful after compositing, extraction, and declusterization.

Importing composite sets

Use File > Import… to bring composites into Genesis.

The current implementation supports import from:

  • delimited composite files (.csv),
  • fixed-width composite files (.dat),
  • Access databases (.mdb, .accdb).

When importing composites from another application, verify the field mapping carefully. In particular:

  • make sure variables are linked to the correct Genesis variables,
  • make sure hole names match the drillholes in the project,
  • make sure the imported support and coordinates match the intended workflow.

Exporting composite sets

Use File > Export… to export one or more composite sets.

Genesis supports several export layouts, including:

  • 3D Sample,
  • 3D Intercept,
  • 2D Intercept,
  • From-To,
  • Standard,
  • All Fields,
  • Average,
  • Sum Weight,
  • Percentile.

Depending on the export type, the output can include items such as:

  • centre coordinates,
  • start and end coordinates,
  • from and to depths,
  • documented length,
  • projected thickness,
  • declusterization weight,
  • composite variables,
  • set-level global values.

Notes on export options

  • 2D Intercept exports projected coordinates and thickness.
  • Average, Sum Weight, and Percentile are summary exports rather than one-record-per-composite exports.
  • Summary exports can use different weighting choices, including None, Total Length, Documented Length, Declust Weight, or a variable from the set.
  • An envelope limit can be applied during export.
  • When exporting several compatible sets, Genesis can place them in a single file.

Creating composites from block models

Two commands are available when you want to relate composites and block model data, but they do not serve the same purpose.

Create From BM…

Create From BM… creates a new composite-style set directly from a block model.

In this case, each block becomes one composite-style record located at the block centre. The new set is built from the block model itself rather than from drillhole intervals.

Practical points:

  • the hole name is set from the block model name,
  • the block centre becomes the composite location,
  • the block model variables are copied into the new set,
  • the block Type field is used as the composite tag when available.

Use this command when you want to treat block model values as a composite-like dataset for comparison, plotting, or other workflows that expect composites.

Create Cross Validate From BM…

Create Cross Validate From BM… starts from an existing composite set and adds block model information to it.

Genesis checks which block contains the centre of each composite. If a composite falls inside a block, it is copied into a new set and the block model values are appended to that composite.

Practical points:

  • the original composite geometry and variables are preserved,
  • only composites whose centres fall inside a block are kept,
  • block model variables are added as extra fields,
  • added block model fields are prefixed with bm_.

Use this command when you want to compare sample-based composite values against the block model values at the same locations, which is why it is useful for cross-validation.

Difference between the two commands

  • Create From BM… converts the block model itself into a composite-style set.
  • Create Cross Validate From BM… keeps the existing composites and enriches them with values taken from the block model.

In short, the first command produces a set of block-centre samples, while the second produces a matched comparison dataset between composites and blocks.

Special variables and advanced outputs

Genesis can also generate additional information for selected composite sets.

Use Generate > Special Variables… to add items such as:

  • SCI (Space Coverage Index),
  • BCT (Block Coverage Tag),
  • global average values,
  • global standard deviation values,
  • percentiles,
  • tag variables such as lithology, alteration, mineralization, or other selected tables,
  • binary variables derived from tag dictionaries.

These variables are mainly intended for sample selection workflows, which are covered in another section.

Use Generate > Export Special Variables… to export the global composite variables for the selected sets.

Practical recommendations

  • Build composites from the correct mineralized interval set before starting statistics or estimation work.
  • Use meaningful set names so exported files and logs remain easy to interpret.
  • Make sure your composites set tag follow your intervals tag and envelope tag.