Table T4. Heavy minerals of Holes 1071A, 1071F, 1072A, and 1073A.
Amphiboles | Different hornblende varieties and Fe/Mg/Mn-amphiboles occur. |
Hornblendes | Brown, green, and blue-green hornblende types can be distinguished on optical grounds. Grains are prismatic, but well-rounded grains also occur. Irregular and jagged edges are common. Etching and grain skeletons are rare. |
Fe/Mg/Mn-amphiboles | Antophyllite and gedrite occur only in a few samples. |
Andalusite | Only colorless varieties with a marked pleochroism occur. Grains are irregularly splintery to subrounded. Corrosion features are rare. |
Apatite | Colorless and brownish yellowish (collophane) varieties occur. The shape of the grains ranges from prismatic with subrounded edges to very well rounded and nearly circular. Irregular grain fragments may also occur. Corrosion features are frequent and intensive. |
Epidote group | Optical identification of zoisite, clinozoisite, and epidote is occasionally ambiguous. Epidote (greenish yellow, pleochroitic minerals) and zoisite/clinozoisite (colorless grains) were distinguished due to color. |
Epidote | Angular, isometric grains are common. Well-rounded grains are rare. Corrosion features and pale colors indicate incipient decomposition. |
Clinozoisite | Short, prismatic, partly subrounded grains occur. Etching features along the edges are frequent. |
Garnet | Three varieties occur: colorless, pale pink, and salmon pink garnets, which all belong to the pyralspite group. Grains are spherical to sharp-cornered irregular and well rounded to angular. Garnets reveal a high variety of corrosion features as described by Grimm (1973). |
Kyanite | Colorless to light blue varieties occur. Mainly prismatic, subrounded grains; inclusions are common. Fibrous etching features may occur along edges. |
Monazit | Grains exhibit a light yellow color and are rounded to well rounded. Grain surfaces are rough and reveal small brownish to black spots. |
Pyroxenes | Orthopyroxenes as well as clinopyroxenes occur. Enstatite (colorless, optically positive, clear pleochroism), hypersthene (pale pink, optically negative, clear pleochroism), diopside (colorless), and augite (green) can be distinguished on optical grounds. |
Augite | Mainly greenish, with short prisms and fragments. Partly rounded, but most of the grains exhibit etching features (hacksaw features along edges and even skeletal grains). |
Diopside | Mostly prismatic, colorless grains. Moderately rounded grains as well as grains exhibiting etching features occur. |
Enstatite | Colorless, prismatic grains. |
Hypersthene | Pale pink, angular to subangular, prismatic grains with a marked pleochroism. Brownish exsolution lamellae are common. |
Rutile | Brownish black and red to reddish black varieties occur. Grains are subrounded to well rounded. |
Sillimanite | Mainly subrounded, prismatic grains and fragments. Rare specimens of fibrolite occur. Etching features are rare. |
Sphene | Colorless, subangular to subrounded grains. |
Staurolite | Grains exhibit variable yellow colors. Most grains are irregular and angular. Some grains are well rounded. Corrosion features are frequent and exhibit warts, frayed edges, and perforated grain skeletons. |
Tourmaline | Brown, colorless; blue and red (with decreasing frequency) varieties occur. Grains are mainly short-prismatic and well rounded. Inclusions are common. |
Zircon | Colorless minerals prevail. Yellowish and pale pink varieties are rare. Mostly well-rounded and spheroidal grains. Some grains exhibit rough and pitted surfaces. Fragments of euhedral forms (some with well-developed zoning) occur. |