TABLE 1. VERTICAL SUCCESSION OF LITHOLOGIC UNITS IN THE HARDING PEGMATITE*

BIOTITE + MUSCOVITE + QUARTZ ± GARNET ± MARGARITE ± SCHORL
A continuous metasomatic aureole, 3-100 cm, with a variable mineralogy dependent on the adjacent host- rock assemblage. The aureole is most prominent in the hanging-wall contact. Important accessory minerals include holmquistite, epidote and titanite.

QUARTZ + ALBITE + MUSCOVITE ± PERTHITE
A continuous wall zone containing a thin, 1-3 cm, border rind of quartz-albite-muscovite in contact with the metasomatic aureole. Beneath this rind is a continuous layer, 0.3-2 m, composed of a coarser aggregate of the same minerals. Beryl, columbite-tantalite, fluorapatite, and microcline are important accessory minerals. Beryl commonly occurs as huge (0.5-1 m) anhedral crystals, hence this zone is often called the beryl zone.

QUARTZ ± ALBITE ± MUSCOVITE
A continuous zone beneath the beryl zone, 0.5-10 m thick. Muscovite, microcline, and cleavelandite are minor accessory minerals.

QUARTZ + LATH SPODUMENE
A continuous zone, up to 14 m thick, in the thicker western portions of the main dike. This zone underlies the quartz zone and is composed of long bladed spodumene laths supported by a massive quartz matrix. The spodumene laths are arranged in a jack-straw fashion and locally are subperpendicular to the hanging- wall contact. Important accessory minerals occurring interstitial to spodumene laths include: beryl, fluorapatite, lepidolite, microcline, and microlite.

MICROCLINE + SPODUMENE + LEPIDOLITE + ALBITE + MUSCOVITE + QUARTZ
This unit forms an elongate lobe in the core of the thick western portion of the dike. The zone is 18 m in maximum thickness and 16-58 m wide. Down plunge, parallel to the dike, it extends for nearly 230 m. This zone is composed of an even-grained (1-10 cm) aggregate of primary quartz, microcline, spodumene, finer albite, and scattered millimeter-size uranium-rich microlite crystals. Lithium-bearing muscovite and lepidolite impregnate the microcline, coloring it pink. Locally this zone grades into pegmatite composed of lepidolite with spodumene; and with decreasing spodumene content, it grades into pure lepidolite replacement bodies. because of its common striking texture, this zone is often referred to as "spotted rock".

CLEAVELANDITE + ROSE MUSCOVITE ± QUARTZ
A replacement unit forming discontinuous masses marginal to the quartz - lath spodumene zone. Rose muscovite replaces spodumene and cleavelandite replaces quartz. Pseudomorphs of rose muscovite after spodumene are common.

CLEAVELANDITE + QUARTZ ± MUSCOVITE
A replacement unit forming highly discontinuous masses throughout the core and wall zone of the dike. Even-grained to radiating cauliflower masses of cleavelandite range from meter-size pods to extensive pseudomorphic zones.

BLOCKY PERTHITE ± QUARTZ ± ALBITE
This zone, dominated by large blocks (0.5-2 m) of cream to pale orange-colored perthitic microcline, occupies basal sections of the dike. Microcline crystals commonly contain fractures filled with albite aplite. This unit is continuous in the eastern extension of the dike and less so in the thick western portion.

QUARTZ + APLITIC ALBITE ± MUSCOVITE
This unit is continuous (up to 3 m thick) in all but the thinner parts of the dike, and also occurs as sporadic small patches (less than 0.5 m) in other units. Small pods of beryl (less than 0.5 m), infrequent columbite- tantalite crystals (less than 10 cm), and scattered quartz-spodumene aggregates (less than 4 cm) pseudomorphic after petalite are important accessories. Locally, veinlets of coarse platy lepidolite penetrate as fracture fillings.