Biotite 3D model with other minerals

The model shown here is flagged as containing biotite. But is that really what's here? And what other minerals are present?

Click the play button (▶) on the model image to launch it. Rotate it and try to make up your mind about whether the patch labelled with the number 1 is biotite, and decide on what other minerals might be here. Use the Guideposts beneath the model to help you out.

Guidepost 1: Are the black patches really biotite?

Factors to consider:

Lustre

Does the lustre resemble that of biotite? What does that mean, given that the appearance of this model is determined in part by choices in how the sample was scanned?

Crystal Habit/Form

Perfectly formed biotite crystals can appear as flattish hexagonal plates, but other crystals can look that way depending on how they're broken.

Cleavage

Biotite has one direction of cleavage (perfect basal cleavage), meaning it breaks into thin, flat sheets.

Guidepost 2: What other minerals are present?

Preliminary Analysis (Not the answer, but some strong hints)

Are the black patches biotite?

If we take the lustre at face value, then no. Biotite is shiner that we see here, but we can't really rely on the lustre being represented 100% accurately. Many of the black patches do appear hexagonal(ish) in some views, and at least one patch looks to have a platy shape from the side. However, it could be argued that some of the black surfaces show two cleavage directions. (Did you spot them?)

What other minerals are present?

A pinkish opaque mineral with two well-developed planes of cleavage (a stepped appearance)
A light grey mineral with no visible cleavage. (It's grey because it's transparent.)
A whitish opaque mineral that may display two planes of cleavage

Conclusions (The actual answer)

Are the black patches biotite?

There are at least two examples of somewhat smaller flat black plates embedded sideways into the sample so that they're visibile edge-on. If biotite is present, those would be the most likely candidates. Otherwise, many of the black patches appear to display two planes of cleavage not at 90°. That would make them amphibole (probably the variety hornblende). The fact that some of those are flattish (amphibole is more prism-shaped) could just be a result of how the sample was broken when it was collected. The presence of both biotite and hornblende are consistent with the fact that the sample is an example of granite.

What other minerals are present?

A pinkish opaque mineral with two well-developed planes of cleavage: Potassium feldspar. The cleavage planes are close to 90°.
A light grey mineral with no visible cleavage. (It's grey because it's transparent.): Quartz. Quartz often resembles broken chunks of ice (which is also a glassy transparent colourless mineral without cleavage).
A whitish opaque mineral that may display two planes of cleavage. Plagioclase feldspar. In some spots, one could argue that there are two planes of cleavage at close to 90°.