Which of the following is an inosilicate amphibole mineral used in highway construction and as railroad ballast?

Question

Accepted Answer

1. Understand the target: the question asks for an "inosilicate amphibole" mineral used in highway construction and railroad ballast.

2. Inosilicate amphiboles: these are double-chain silicates with the basic silica unit $Si_4O_{11}$ (Si:O = $4:11$).

3. Evaluate options:
   - (1) Shale: a fine‑grained sedimentary rock, not an inosilicate mineral.
   - (2) Olivine: a nesosilicate (isolated tetrahedra) with formula $ (Mg,Fe)_2SiO_4$, not an amphibole.
   - (3) Geyserite: a form of amorphous silica (SiO$_2$) deposited by hot springs, not an amphibole.
   - (4) Hornblende: a common dark amphibole (double‑chain inosilicate) found in igneous/metamorphic rocks; hornblende-bearing rock is commonly crushed and used as aggregate for highways and railroad ballast.

4. Conclusion: the correct choice is (4) Hornblende, which corresponds to option d.

FINAL_ANSWER: d

Answer

Answer

Answer