Minerals appear in many different ways. Opaque minerals do not allow light to pass through them. Isotropic minerals allow light to pass through it the same way no matter how the mineral is held. Anisotropic minerals reflects light depending up how the grains lay.
What mineral that appears in transparent hexagonal crystals
luster
Galena mineral typically appears with a streak color that is gray to black.
Hematite is a mineral that commonly appears in a metallic gray or black color, but when it is powdered, it produces a reddish-brown streak. This difference in color is due to the way light interacts with the mineral's crystalline structure versus its powdered form. The streak test is often used in mineral identification to reveal these contrasting colors.
The property a mineral would have if it appears like a new quarter in reflected light is metallic luster. This means the mineral has a shiny, reflective surface like metal, similar to the appearance of a new quarter.
The way it functions and appears
Asterism
Quartz can appear in transparent hexagonal crystals.
Halite is a non-metallic mineral. It has a glassy or vitreous luster and typically appears transparent or translucent.
The way a mineral reflects light is its luster. Luster is determined by the way light interacts with the surface of the mineral, producing characteristics like metallic, vitreous, silky, or dull appearances.
The observable color is the least dependable method of mineral identification.
There is insufficient information to answer this question. What mineral? Also, it seems hard to imagine that only one explorer used a given mineral to find his/her way.