* Plagioclase feldspar: This is a major component of felsic rocks, often with a higher proportion of sodium-rich plagioclase (albite) than calcium-rich plagioclase (anorthite).

* Dark silicate minerals: Felsic rocks generally have a lower percentage of dark silicate minerals (like pyroxene, amphibole, or biotite) compared to other igneous rock types.

* Composition: The exact composition of the rock will depend on the exact percentages of plagioclase feldspar and dark silicate minerals (represented by "W" in your question). However, the overall composition will be rich in silica (SiO2), hence the term "felsic."

Examples of felsic rocks:

* Granite: A common felsic rock with a coarse-grained texture.

* Rhyolite: A felsic rock with a fine-grained texture.

* Granodiorite: A felsic rock with a slightly higher percentage of dark silicate minerals than granite.

Key characteristics of felsic rocks:

* Light color: They typically have a light gray, pink, or white color due to the dominance of feldspar.

* High silica content: They are rich in silica (SiO2), which gives them a relatively high melting point.

* Low density: They are less dense than other igneous rocks.

To determine the exact composition of your rock, you would need more information:

* The specific type of plagioclase feldspar: Knowing whether it's albite, oligoclase, or andesine will provide further insight.

* The exact percentage of dark silicate minerals ("W"): This will influence the specific rock type (e.g., granite vs. granodiorite).

* Additional minerals: Other minerals, like quartz or mica, may be present, impacting the overall composition.

Ultimately, a more detailed analysis is needed to precisely classify your rock.