Question

Estimate the percentage of each mineral in rhyolite (look under the ""o"" in rhyolite).

1. Potassium feldspar _______ %
2. Quartz ___________%
3. Plagioclase feldspar ___________%
4. Biotite mica ___________%
5. Amphiboles (hornblende) ___________%

Answer 1

Rhyolite, being a felsic extrusive rock, is composed mainly of quartz and potassium feldspar, with smaller quantities of plagioclase, biotite, and amphiboles.

Step-by-step explanation:

Rhyolite is a felsic, extrusive igneous rock with a similar mineral composition as granite but with an aphanitic texture, meaning its crystals are too small to be seen without magnification. The approximate mineral content in rhyolite is as follows:

• Quartz: 20-60%
• Potassium Feldspar (Orthoclase/Microcline): 20-60%
• Plagioclase Feldspar: 10-35%
• Biotite Mica: 0-10%
• Amphiboles (Hornblende): 0-5%

These estimations are based on the general range of mineral content typically found in rhyolitic rocks. Since rhyolite has a high viscosity when it erupts, it allows for the formation of fine crystals of these minerals to create the smooth texture observed. In summary, quartz and potassium feldspar are the dominant components, with variable amounts of plagioclase, and minor components of biotite and amphiboles, as is characteristic for a rock of felsic composition like rhyolite.

Answer 2

Potassium feldspar 25%

Quartz 40%

Plagioclase feldspar 20%

Biotite mica 10%

Amphiboles (hornblende) 5%

Step-by-step explanation:

Rhyolite is a type of igneous rock that is composed mainly of quartz, potassium feldspar, and plagioclase feldspar, with smaller amounts of biotite mica and amphiboles (hornblende). To estimate the percentage of each mineral in rhyolite, we can refer to the typical mineral composition of this rock type. Based on geological studies and analyses, it is estimated that rhyolite consists of approximately 25% potassium feldspar, 40% quartz, 20% plagioclase feldspar, 10% biotite mica, and 5% amphiboles (hornblende).

The estimation of these percentages is based on the average mineral composition found in rhyolite samples from various geological formations. These values may vary slightly depending on the specific location and geological conditions where the rhyolite was formed. However, these estimates provide a general understanding of the mineral distribution within rhyolite and are widely accepted in the field of geology.

It’s important to note that while these percentages provide a good approximation of the mineral composition in rhyolite, variations can occur due to factors such as the presence of accessory minerals or specific geological processes that may have influenced the rock’s formation.