Question

Needle-like in appearance, in ultramafic lava flows:

a. rhyolite
b. dacite
c. ophiolite
d. spinifex
e. none of above

Answer 1

The needle-like structures in ultramafic lava flows are called spinifex. Spinifex is a term used to describe the characteristic growth pattern of mineral crystals in certain types of lava flows.

Step-by-step explanation:

The needle-like structures in ultramafic lava flows are called spinifex. Spinifex is a term used to describe the characteristic growth pattern of mineral crystals in certain types of lava flows. It is commonly associated with ultramafic lava flows, which are rich in minerals such as olivine and pyroxene.

Characteristics of spinifex:

1. Color: Varies depending on the mineral composition of the lava flow.
2. Texture: Aphanitic (fine-grained) with needle-like mineral crystals.
3. Mineral content: Predominantly olivine and pyroxene.